summaryrefslogtreecommitdiffstats
path: root/kernel
Commit message (Collapse)AuthorAgeFilesLines
* tracing: uprobes: Fix typo in pr_fmt stringAndreas Ziegler2019-02-151-1/+1
| | | | | | | | | | | | | | | | | | | commit ea6eb5e7d15e1838de335609994b4546e2abcaaf upstream. The subsystem-specific message prefix for uprobes was also "trace_kprobe: " instead of "trace_uprobe: " as described in the original commit message. Link: http://lkml.kernel.org/r/20190117133023.19292-1-andreas.ziegler@fau.de Cc: Ingo Molnar <mingo@redhat.com> Cc: stable@vger.kernel.org Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Fixes: 7257634135c24 ("tracing/probe: Show subsystem name in messages") Signed-off-by: Andreas Ziegler <andreas.ziegler@fau.de> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* signal: Better detection of synchronous signalsEric W. Biederman2019-02-151-1/+51
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 7146db3317c67b517258cb5e1b08af387da0618b upstream. Recently syzkaller was able to create unkillablle processes by creating a timer that is delivered as a thread local signal on SIGHUP, and receiving SIGHUP SA_NODEFERER. Ultimately causing a loop failing to deliver SIGHUP but always trying. When the stack overflows delivery of SIGHUP fails and force_sigsegv is called. Unfortunately because SIGSEGV is numerically higher than SIGHUP next_signal tries again to deliver a SIGHUP. From a quality of implementation standpoint attempting to deliver the timer SIGHUP signal is wrong. We should attempt to deliver the synchronous SIGSEGV signal we just forced. We can make that happening in a fairly straight forward manner by instead of just looking at the signal number we also look at the si_code. In particular for exceptions (aka synchronous signals) the si_code is always greater than 0. That still has the potential to pick up a number of asynchronous signals as in a few cases the same si_codes that are used for synchronous signals are also used for asynchronous signals, and SI_KERNEL is also included in the list of possible si_codes. Still the heuristic is much better and timer signals are definitely excluded. Which is enough to prevent all known ways for someone sending a process signals fast enough to cause unexpected and arguably incorrect behavior. Cc: stable@vger.kernel.org Fixes: a27341cd5fcb ("Prioritize synchronous signals over 'normal' signals") Tested-by: Dmitry Vyukov <dvyukov@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* signal: Always notice exiting tasksEric W. Biederman2019-02-151-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 35634ffa1751b6efd8cf75010b509dcb0263e29b upstream. Recently syzkaller was able to create unkillablle processes by creating a timer that is delivered as a thread local signal on SIGHUP, and receiving SIGHUP SA_NODEFERER. Ultimately causing a loop failing to deliver SIGHUP but always trying. Upon examination it turns out part of the problem is actually most of the solution. Since 2.5 signal delivery has found all fatal signals, marked the signal group for death, and queued SIGKILL in every threads thread queue relying on signal->group_exit_code to preserve the information of which was the actual fatal signal. The conversion of all fatal signals to SIGKILL results in the synchronous signal heuristic in next_signal kicking in and preferring SIGHUP to SIGKILL. Which is especially problematic as all fatal signals have already been transformed into SIGKILL. Instead of dequeueing signals and depending upon SIGKILL to be the first signal dequeued, first test if the signal group has already been marked for death. This guarantees that nothing in the signal queue can prevent a process that needs to exit from exiting. Cc: stable@vger.kernel.org Tested-by: Dmitry Vyukov <dvyukov@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Ref: ebf5ebe31d2c ("[PATCH] signal-fixes-2.5.59-A4") History Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* perf/core: Don't WARN() for impossible ring-buffer sizesMark Rutland2019-02-121-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 9dff0aa95a324e262ffb03f425d00e4751f3294e upstream. The perf tool uses /proc/sys/kernel/perf_event_mlock_kb to determine how large its ringbuffer mmap should be. This can be configured to arbitrary values, which can be larger than the maximum possible allocation from kmalloc. When this is configured to a suitably large value (e.g. thanks to the perf fuzzer), attempting to use perf record triggers a WARN_ON_ONCE() in __alloc_pages_nodemask(): WARNING: CPU: 2 PID: 5666 at mm/page_alloc.c:4511 __alloc_pages_nodemask+0x3f8/0xbc8 Let's avoid this by checking that the requested allocation is possible before calling kzalloc. Reported-by: Julien Thierry <julien.thierry@arm.com> Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Julien Thierry <julien.thierry@arm.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: <stable@vger.kernel.org> Link: https://lkml.kernel.org/r/20190110142745.25495-1-mark.rutland@arm.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* cpu/hotplug: Fix "SMT disabled by BIOS" detection for KVMJosh Poimboeuf2019-02-123-31/+5Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit b284909abad48b07d3071a9fc9b5692b3e64914b upstream. With the following commit: 73d5e2b47264 ("cpu/hotplug: detect SMT disabled by BIOS") ... the hotplug code attempted to detect when SMT was disabled by BIOS, in which case it reported SMT as permanently disabled. However, that code broke a virt hotplug scenario, where the guest is booted with only primary CPU threads, and a sibling is brought online later. The problem is that there doesn't seem to be a way to reliably distinguish between the HW "SMT disabled by BIOS" case and the virt "sibling not yet brought online" case. So the above-mentioned commit was a bit misguided, as it permanently disabled SMT for both cases, preventing future virt sibling hotplugs. Going back and reviewing the original problems which were attempted to be solved by that commit, when SMT was disabled in BIOS: 1) /sys/devices/system/cpu/smt/control showed "on" instead of "notsupported"; and 2) vmx_vm_init() was incorrectly showing the L1TF_MSG_SMT warning. I'd propose that we instead consider #1 above to not actually be a problem. Because, at least in the virt case, it's possible that SMT wasn't disabled by BIOS and a sibling thread could be brought online later. So it makes sense to just always default the smt control to "on" to allow for that possibility (assuming cpuid indicates that the CPU supports SMT). The real problem is #2, which has a simple fix: change vmx_vm_init() to query the actual current SMT state -- i.e., whether any siblings are currently online -- instead of looking at the SMT "control" sysfs value. So fix it by: a) reverting the original "fix" and its followup fix: 73d5e2b47264 ("cpu/hotplug: detect SMT disabled by BIOS") bc2d8d262cba ("cpu/hotplug: Fix SMT supported evaluation") and b) changing vmx_vm_init() to query the actual current SMT state -- instead of the sysfs control value -- to determine whether the L1TF warning is needed. This also requires the 'sched_smt_present' variable to exported, instead of 'cpu_smt_control'. Fixes: 73d5e2b47264 ("cpu/hotplug: detect SMT disabled by BIOS") Reported-by: Igor Mammedov <imammedo@redhat.com> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Joe Mario <jmario@redhat.com> Cc: Jiri Kosina <jikos@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: kvm@vger.kernel.org Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/e3a85d585da28cc333ecbc1e78ee9216e6da9396.1548794349.git.jpoimboe@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* futex: Handle early deadlock return correctlyThomas Gleixner2019-02-122-15/+50
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 1a1fb985f2e2b85ec0d3dc2e519ee48389ec2434 upstream. commit 56222b212e8e ("futex: Drop hb->lock before enqueueing on the rtmutex") changed the locking rules in the futex code so that the hash bucket lock is not longer held while the waiter is enqueued into the rtmutex wait list. This made the lock and the unlock path symmetric, but unfortunately the possible early exit from __rt_mutex_proxy_start() due to a detected deadlock was not updated accordingly. That allows a concurrent unlocker to observe inconsitent state which triggers the warning in the unlock path. futex_lock_pi() futex_unlock_pi() lock(hb->lock) queue(hb_waiter) lock(hb->lock) lock(rtmutex->wait_lock) unlock(hb->lock) // acquired hb->lock hb_waiter = futex_top_waiter() lock(rtmutex->wait_lock) __rt_mutex_proxy_start() ---> fail remove(rtmutex_waiter); ---> returns -EDEADLOCK unlock(rtmutex->wait_lock) // acquired wait_lock wake_futex_pi() rt_mutex_next_owner() --> returns NULL --> WARN lock(hb->lock) unqueue(hb_waiter) The problem is caused by the remove(rtmutex_waiter) in the failure case of __rt_mutex_proxy_start() as this lets the unlocker observe a waiter in the hash bucket but no waiter on the rtmutex, i.e. inconsistent state. The original commit handles this correctly for the other early return cases (timeout, signal) by delaying the removal of the rtmutex waiter until the returning task reacquired the hash bucket lock. Treat the failure case of __rt_mutex_proxy_start() in the same way and let the existing cleanup code handle the eventual handover of the rtmutex gracefully. The regular rt_mutex_proxy_start() gains the rtmutex waiter removal for the failure case, so that the other callsites are still operating correctly. Add proper comments to the code so all these details are fully documented. Thanks to Peter for helping with the analysis and writing the really valuable code comments. Fixes: 56222b212e8e ("futex: Drop hb->lock before enqueueing on the rtmutex") Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com> Co-developed-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: linux-s390@vger.kernel.org Cc: Stefan Liebler <stli@linux.ibm.com> Cc: Sebastian Sewior <bigeasy@linutronix.de> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/alpine.DEB.2.21.1901292311410.1950@nanos.tec.linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* kernel/kcov.c: mark write_comp_data() as notraceAnders Roxell2019-02-121-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit 634724431607f6f46c495dfef801a1c8b44a96d9 ] Since __sanitizer_cov_trace_const_cmp4 is marked as notrace, the function called from __sanitizer_cov_trace_const_cmp4 shouldn't be traceable either. ftrace_graph_caller() gets called every time func write_comp_data() gets called if it isn't marked 'notrace'. This is the backtrace from gdb: #0 ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:179 #1 0xffffff8010201920 in ftrace_caller () at ../arch/arm64/kernel/entry-ftrace.S:151 #2 0xffffff8010439714 in write_comp_data (type=5, arg1=0, arg2=0, ip=18446743524224276596) at ../kernel/kcov.c:116 #3 0xffffff8010439894 in __sanitizer_cov_trace_const_cmp4 (arg1=<optimized out>, arg2=<optimized out>) at ../kernel/kcov.c:188 #4 0xffffff8010201874 in prepare_ftrace_return (self_addr=18446743524226602768, parent=0xffffff801014b918, frame_pointer=18446743524223531344) at ./include/generated/atomic-instrumented.h:27 #5 0xffffff801020194c in ftrace_graph_caller () at ../arch/arm64/kernel/entry-ftrace.S:182 Rework so that write_comp_data() that are called from __sanitizer_cov_trace_*_cmp*() are marked as 'notrace'. Commit 903e8ff86753 ("kernel/kcov.c: mark funcs in __sanitizer_cov_trace_pc() as notrace") missed to mark write_comp_data() as 'notrace'. When that patch was created gcc-7 was used. In lib/Kconfig.debug config KCOV_ENABLE_COMPARISONS depends on $(cc-option,-fsanitize-coverage=trace-cmp) That code path isn't hit with gcc-7. However, it were that with gcc-8. Link: http://lkml.kernel.org/r/20181206143011.23719-1-anders.roxell@linaro.org Signed-off-by: Anders Roxell <anders.roxell@linaro.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Co-developed-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* kernel/hung_task.c: force console verbose before panicLiu, Chuansheng2019-02-121-7/+5Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit 168e06f7937d96c7222037d8a05565e8a6eb00fe ] Based on commit 401c636a0eeb ("kernel/hung_task.c: show all hung tasks before panic"), we could get the call stack of hung task. However, if the console loglevel is not high, we still can not see the useful panic information in practice, and in most cases users don't set console loglevel to high level. This patch is to force console verbose before system panic, so that the real useful information can be seen in the console, instead of being like the following, which doesn't have hung task information. INFO: task init:1 blocked for more than 120 seconds. Tainted: G U W 4.19.0-quilt-2e5dc0ac-g51b6c21d76cc #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. Kernel panic - not syncing: hung_task: blocked tasks CPU: 2 PID: 479 Comm: khungtaskd Tainted: G U W 4.19.0-quilt-2e5dc0ac-g51b6c21d76cc #1 Call Trace: dump_stack+0x4f/0x65 panic+0xde/0x231 watchdog+0x290/0x410 kthread+0x12c/0x150 ret_from_fork+0x35/0x40 reboot: panic mode set: p,w Kernel Offset: 0x34000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) Link: http://lkml.kernel.org/r/27240C0AC20F114CBF8149A2696CBE4A6015B675@SHSMSX101.ccr.corp.intel.com Signed-off-by: Chuansheng Liu <chuansheng.liu@intel.com> Reviewed-by: Petr Mladek <pmladek@suse.com> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* proc/sysctl: fix return error for proc_doulongvec_minmax()Cheng Lin2019-02-121-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit 09be178400829dddc1189b50a7888495dd26aa84 ] If the number of input parameters is less than the total parameters, an EINVAL error will be returned. For example, we use proc_doulongvec_minmax to pass up to two parameters with kern_table: { .procname = "monitor_signals", .data = &monitor_sigs, .maxlen = 2*sizeof(unsigned long), .mode = 0644, .proc_handler = proc_doulongvec_minmax, }, Reproduce: When passing two parameters, it's work normal. But passing only one parameter, an error "Invalid argument"(EINVAL) is returned. [root@cl150 ~]# echo 1 2 > /proc/sys/kernel/monitor_signals [root@cl150 ~]# cat /proc/sys/kernel/monitor_signals 1 2 [root@cl150 ~]# echo 3 > /proc/sys/kernel/monitor_signals -bash: echo: write error: Invalid argument [root@cl150 ~]# echo $? 1 [root@cl150 ~]# cat /proc/sys/kernel/monitor_signals 3 2 [root@cl150 ~]# The following is the result after apply this patch. No error is returned when the number of input parameters is less than the total parameters. [root@cl150 ~]# echo 1 2 > /proc/sys/kernel/monitor_signals [root@cl150 ~]# cat /proc/sys/kernel/monitor_signals 1 2 [root@cl150 ~]# echo 3 > /proc/sys/kernel/monitor_signals [root@cl150 ~]# echo $? 0 [root@cl150 ~]# cat /proc/sys/kernel/monitor_signals 3 2 [root@cl150 ~]# There are three processing functions dealing with digital parameters, __do_proc_dointvec/__do_proc_douintvec/__do_proc_doulongvec_minmax. This patch deals with __do_proc_doulongvec_minmax, just as __do_proc_dointvec does, adding a check for parameters 'left'. In __do_proc_douintvec, its code implementation explicitly does not support multiple inputs. static int __do_proc_douintvec(...){ ... /* * Arrays are not supported, keep this simple. *Do not* add * support for them. */ if (vleft != 1) { *lenp = 0; return -EINVAL; } ... } So, just __do_proc_doulongvec_minmax has the problem. And most use of proc_doulongvec_minmax/proc_doulongvec_ms_jiffies_minmax just have one parameter. Link: http://lkml.kernel.org/r/1544081775-15720-1-git-send-email-cheng.lin130@zte.com.cn Signed-off-by: Cheng Lin <cheng.lin130@zte.com.cn> Acked-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* kernel/hung_task.c: break RCU locks based on jiffiesTetsuo Handa2019-02-121-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit 304ae42739b108305f8d7b3eb3c1aec7c2b643a9 ] check_hung_uninterruptible_tasks() is currently calling rcu_lock_break() for every 1024 threads. But check_hung_task() is very slow if printk() was called, and is very fast otherwise. If many threads within some 1024 threads called printk(), the RCU grace period might be extended enough to trigger RCU stall warnings. Therefore, calling rcu_lock_break() for every some fixed jiffies will be safer. Link: http://lkml.kernel.org/r/1544800658-11423-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Paul E. McKenney <paulmck@linux.ibm.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com> Cc: Vitaly Kuznetsov <vkuznets@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* kdb: Don't back trace on a cpu that didn't round upDouglas Anderson2019-02-123-8/+14
| | | | | | | | | | | | | | | [ Upstream commit 162bc7f5afd75b72acbe3c5f3488ef7e64a3fe36 ] If you have a CPU that fails to round up and then run 'btc' you'll end up crashing in kdb becaue we dereferenced NULL. Let's add a check. It's wise to also set the task to NULL when leaving the debugger so that if we fail to round up on a later entry into the debugger we won't backtrace a stale task. Signed-off-by: Douglas Anderson <dianders@chromium.org> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* cgroup: fix parsing empty mount option stringOndrej Mosnacek2019-02-121-1/+1
| | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit e250d91d65750a0c0c62483ac4f9f357e7317617 ] This fixes the case where all mount options specified are consumed by an LSM and all that's left is an empty string. In this case cgroupfs should accept the string and not fail. How to reproduce (with SELinux enabled): # umount /sys/fs/cgroup/unified # mount -o context=system_u:object_r:cgroup_t:s0 -t cgroup2 cgroup2 /sys/fs/cgroup/unified mount: /sys/fs/cgroup/unified: wrong fs type, bad option, bad superblock on cgroup2, missing codepage or helper program, or other error. # dmesg | tail -n 1 [ 31.575952] cgroup: cgroup2: unknown option "" Fixes: 67e9c74b8a87 ("cgroup: replace __DEVEL__sane_behavior with cgroup2 fs type") [NOTE: should apply on top of commit 5136f6365ce3 ("cgroup: implement "nsdelegate" mount option"), older versions need manual rebase] Suggested-by: Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* kobject: return error code if writing /sys/.../uevent failsPeter Rajnoha2019-02-121-2/+4
| | | | | | | | | | | | | | | | | [ Upstream commit df44b479654f62b478c18ee4d8bc4e9f897a9844 ] Propagate error code back to userspace if writing the /sys/.../uevent file fails. Before, the write operation always returned with success, even if we failed to recognize the input string or if we failed to generate the uevent itself. With the error codes properly propagated back to userspace, we are able to react in userspace accordingly by not assuming and awaiting a uevent that is not delivered. Signed-off-by: Peter Rajnoha <prajnoha@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* timekeeping: Use proper seqcount initializerBart Van Assche2019-02-121-1/+3
| | | | | | | | | | | | | | | | | | | | | [ Upstream commit ce10a5b3954f2514af726beb78ed8d7350c5e41c ] tk_core.seq is initialized open coded, but that misses to initialize the lockdep map when lockdep is enabled. Lockdep splats involving tk_core seq consequently lack a name and are hard to read. Use the proper initializer which takes care of the lockdep map initialization. [ tglx: Massaged changelog ] Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: peterz@infradead.org Cc: tj@kernel.org Cc: johannes.berg@intel.com Link: https://lkml.kernel.org/r/20181128234325.110011-12-bvanassche@acm.org Signed-off-by: Sasha Levin <sashal@kernel.org>
* genirq/affinity: Spread IRQs to all available NUMA nodesLong Li2019-02-121-3/+2Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit b82592199032bf7c778f861b936287e37ebc9f62 ] If the number of NUMA nodes exceeds the number of MSI/MSI-X interrupts which are allocated for a device, the interrupt affinity spreading code fails to spread them across all nodes. The reason is, that the spreading code starts from node 0 and continues up to the number of interrupts requested for allocation. This leaves the nodes past the last interrupt unused. This results in interrupt concentration on the first nodes which violates the assumption of the block layer that all nodes are covered evenly. As a consequence the NUMA nodes above the number of interrupts are all assigned to hardware queue 0 and therefore NUMA node 0, which results in bad performance and has CPU hotplug implications, because queue 0 gets shut down when the last CPU of node 0 is offlined. Go over all NUMA nodes and assign them round-robin to all requested interrupts to solve this. [ tglx: Massaged changelog ] Signed-off-by: Long Li <longli@microsoft.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Cc: Michael Kelley <mikelley@microsoft.com> Link: https://lkml.kernel.org/r/20181102180248.13583-1-longli@linuxonhyperv.com Signed-off-by: Sasha Levin <sashal@kernel.org>
* kernel/exit.c: release ptraced tasks before zap_pid_ns_processesAndrei Vagin2019-02-061-2/+10
| | | | | | | | | | | | | | | | | | | | | | | | | commit 8fb335e078378c8426fabeed1ebee1fbf915690c upstream. Currently, exit_ptrace() adds all ptraced tasks in a dead list, then zap_pid_ns_processes() waits on all tasks in a current pidns, and only then are tasks from the dead list released. zap_pid_ns_processes() can get stuck on waiting tasks from the dead list. In this case, we will have one unkillable process with one or more dead children. Thanks to Oleg for the advice to release tasks in find_child_reaper(). Link: http://lkml.kernel.org/r/20190110175200.12442-1-avagin@gmail.com Fixes: 7c8bd2322c7f ("exit: ptrace: shift "reap dead" code from exit_ptrace() to forget_original_parent()") Signed-off-by: Andrei Vagin <avagin@gmail.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* bpf: fix inner map masking to prevent oob under speculationDaniel Borkmann2019-01-311-2/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ commit 9d5564ddcf2a0f5ba3fa1c3a1f8a1b59ad309553 upstream ] During review I noticed that inner meta map setup for map in map is buggy in that it does not propagate all needed data from the reference map which the verifier is later accessing. In particular one such case is index masking to prevent out of bounds access under speculative execution due to missing the map's unpriv_array/index_mask field propagation. Fix this such that the verifier is generating the correct code for inlined lookups in case of unpriviledged use. Before patch (test_verifier's 'map in map access' dump): # bpftool prog dump xla id 3 0: (62) *(u32 *)(r10 -4) = 0 1: (bf) r2 = r10 2: (07) r2 += -4 3: (18) r1 = map[id:4] 5: (07) r1 += 272 | 6: (61) r0 = *(u32 *)(r2 +0) | 7: (35) if r0 >= 0x1 goto pc+6 | Inlined map in map lookup 8: (54) (u32) r0 &= (u32) 0 | with index masking for 9: (67) r0 <<= 3 | map->unpriv_array. 10: (0f) r0 += r1 | 11: (79) r0 = *(u64 *)(r0 +0) | 12: (15) if r0 == 0x0 goto pc+1 | 13: (05) goto pc+1 | 14: (b7) r0 = 0 | 15: (15) if r0 == 0x0 goto pc+11 16: (62) *(u32 *)(r10 -4) = 0 17: (bf) r2 = r10 18: (07) r2 += -4 19: (bf) r1 = r0 20: (07) r1 += 272 | 21: (61) r0 = *(u32 *)(r2 +0) | Index masking missing (!) 22: (35) if r0 >= 0x1 goto pc+3 | for inner map despite 23: (67) r0 <<= 3 | map->unpriv_array set. 24: (0f) r0 += r1 | 25: (05) goto pc+1 | 26: (b7) r0 = 0 | 27: (b7) r0 = 0 28: (95) exit After patch: # bpftool prog dump xla id 1 0: (62) *(u32 *)(r10 -4) = 0 1: (bf) r2 = r10 2: (07) r2 += -4 3: (18) r1 = map[id:2] 5: (07) r1 += 272 | 6: (61) r0 = *(u32 *)(r2 +0) | 7: (35) if r0 >= 0x1 goto pc+6 | Same inlined map in map lookup 8: (54) (u32) r0 &= (u32) 0 | with index masking due to 9: (67) r0 <<= 3 | map->unpriv_array. 10: (0f) r0 += r1 | 11: (79) r0 = *(u64 *)(r0 +0) | 12: (15) if r0 == 0x0 goto pc+1 | 13: (05) goto pc+1 | 14: (b7) r0 = 0 | 15: (15) if r0 == 0x0 goto pc+12 16: (62) *(u32 *)(r10 -4) = 0 17: (bf) r2 = r10 18: (07) r2 += -4 19: (bf) r1 = r0 20: (07) r1 += 272 | 21: (61) r0 = *(u32 *)(r2 +0) | 22: (35) if r0 >= 0x1 goto pc+4 | Now fixed inlined inner map 23: (54) (u32) r0 &= (u32) 0 | lookup with proper index masking 24: (67) r0 <<= 3 | for map->unpriv_array. 25: (0f) r0 += r1 | 26: (05) goto pc+1 | 27: (b7) r0 = 0 | 28: (b7) r0 = 0 29: (95) exit Fixes: b2157399cc98 ("bpf: prevent out-of-bounds speculation") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
* bpf: fix sanitation of alu op with pointer / scalar type from different pathsDaniel Borkmann2019-01-311-13/+48
| | | | | | | | | | | | | | | | | | | | | [ commit d3bd7413e0ca40b60cf60d4003246d067cafdeda upstream ] While 979d63d50c0c ("bpf: prevent out of bounds speculation on pointer arithmetic") took care of rejecting alu op on pointer when e.g. pointer came from two different map values with different map properties such as value size, Jann reported that a case was not covered yet when a given alu op is used in both "ptr_reg += reg" and "numeric_reg += reg" from different branches where we would incorrectly try to sanitize based on the pointer's limit. Catch this corner case and reject the program instead. Fixes: 979d63d50c0c ("bpf: prevent out of bounds speculation on pointer arithmetic") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
* bpf: prevent out of bounds speculation on pointer arithmeticDaniel Borkmann2019-01-311-7/+179
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ commit 979d63d50c0c0f7bc537bf821e056cc9fe5abd38 upstream ] Jann reported that the original commit back in b2157399cc98 ("bpf: prevent out-of-bounds speculation") was not sufficient to stop CPU from speculating out of bounds memory access: While b2157399cc98 only focussed on masking array map access for unprivileged users for tail calls and data access such that the user provided index gets sanitized from BPF program and syscall side, there is still a more generic form affected from BPF programs that applies to most maps that hold user data in relation to dynamic map access when dealing with unknown scalars or "slow" known scalars as access offset, for example: - Load a map value pointer into R6 - Load an index into R7 - Do a slow computation (e.g. with a memory dependency) that loads a limit into R8 (e.g. load the limit from a map for high latency, then mask it to make the verifier happy) - Exit if R7 >= R8 (mispredicted branch) - Load R0 = R6[R7] - Load R0 = R6[R0] For unknown scalars there are two options in the BPF verifier where we could derive knowledge from in order to guarantee safe access to the memory: i) While </>/<=/>= variants won't allow to derive any lower or upper bounds from the unknown scalar where it would be safe to add it to the map value pointer, it is possible through ==/!= test however. ii) another option is to transform the unknown scalar into a known scalar, for example, through ALU ops combination such as R &= <imm> followed by R |= <imm> or any similar combination where the original information from the unknown scalar would be destroyed entirely leaving R with a constant. The initial slow load still precedes the latter ALU ops on that register, so the CPU executes speculatively from that point. Once we have the known scalar, any compare operation would work then. A third option only involving registers with known scalars could be crafted as described in [0] where a CPU port (e.g. Slow Int unit) would be filled with many dependent computations such that the subsequent condition depending on its outcome has to wait for evaluation on its execution port and thereby executing speculatively if the speculated code can be scheduled on a different execution port, or any other form of mistraining as described in [1], for example. Given this is not limited to only unknown scalars, not only map but also stack access is affected since both is accessible for unprivileged users and could potentially be used for out of bounds access under speculation. In order to prevent any of these cases, the verifier is now sanitizing pointer arithmetic on the offset such that any out of bounds speculation would be masked in a way where the pointer arithmetic result in the destination register will stay unchanged, meaning offset masked into zero similar as in array_index_nospec() case. With regards to implementation, there are three options that were considered: i) new insn for sanitation, ii) push/pop insn and sanitation as inlined BPF, iii) reuse of ax register and sanitation as inlined BPF. Option i) has the downside that we end up using from reserved bits in the opcode space, but also that we would require each JIT to emit masking as native arch opcodes meaning mitigation would have slow adoption till everyone implements it eventually which is counter-productive. Option ii) and iii) have both in common that a temporary register is needed in order to implement the sanitation as inlined BPF since we are not allowed to modify the source register. While a push / pop insn in ii) would be useful to have in any case, it requires once again that every JIT needs to implement it first. While possible, amount of changes needed would also be unsuitable for a -stable patch. Therefore, the path which has fewer changes, less BPF instructions for the mitigation and does not require anything to be changed in the JITs is option iii) which this work is pursuing. The ax register is already mapped to a register in all JITs (modulo arm32 where it's mapped to stack as various other BPF registers there) and used in constant blinding for JITs-only so far. It can be reused for verifier rewrites under certain constraints. The interpreter's tmp "register" has therefore been remapped into extending the register set with hidden ax register and reusing that for a number of instructions that needed the prior temporary variable internally (e.g. div, mod). This allows for zero increase in stack space usage in the interpreter, and enables (restricted) generic use in rewrites otherwise as long as such a patchlet does not make use of these instructions. The sanitation mask is dynamic and relative to the offset the map value or stack pointer currently holds. There are various cases that need to be taken under consideration for the masking, e.g. such operation could look as follows: ptr += val or val += ptr or ptr -= val. Thus, the value to be sanitized could reside either in source or in destination register, and the limit is different depending on whether the ALU op is addition or subtraction and depending on the current known and bounded offset. The limit is derived as follows: limit := max_value_size - (smin_value + off). For subtraction: limit := umax_value + off. This holds because we do not allow any pointer arithmetic that would temporarily go out of bounds or would have an unknown value with mixed signed bounds where it is unclear at verification time whether the actual runtime value would be either negative or positive. For example, we have a derived map pointer value with constant offset and bounded one, so limit based on smin_value works because the verifier requires that statically analyzed arithmetic on the pointer must be in bounds, and thus it checks if resulting smin_value + off and umax_value + off is still within map value bounds at time of arithmetic in addition to time of access. Similarly, for the case of stack access we derive the limit as follows: MAX_BPF_STACK + off for subtraction and -off for the case of addition where off := ptr_reg->off + ptr_reg->var_off.value. Subtraction is a special case for the masking which can be in form of ptr += -val, ptr -= -val, or ptr -= val. In the first two cases where we know that the value is negative, we need to temporarily negate the value in order to do the sanitation on a positive value where we later swap the ALU op, and restore original source register if the value was in source. The sanitation of pointer arithmetic alone is still not fully sufficient as is, since a scenario like the following could happen ... PTR += 0x1000 (e.g. K-based imm) PTR -= BIG_NUMBER_WITH_SLOW_COMPARISON PTR += 0x1000 PTR -= BIG_NUMBER_WITH_SLOW_COMPARISON [...] ... which under speculation could end up as ... PTR += 0x1000 PTR -= 0 [ truncated by mitigation ] PTR += 0x1000 PTR -= 0 [ truncated by mitigation ] [...] ... and therefore still access out of bounds. To prevent such case, the verifier is also analyzing safety for potential out of bounds access under speculative execution. Meaning, it is also simulating pointer access under truncation. We therefore "branch off" and push the current verification state after the ALU operation with known 0 to the verification stack for later analysis. Given the current path analysis succeeded it is likely that the one under speculation can be pruned. In any case, it is also subject to existing complexity limits and therefore anything beyond this point will be rejected. In terms of pruning, it needs to be ensured that the verification state from speculative execution simulation must never prune a non-speculative execution path, therefore, we mark verifier state accordingly at the time of push_stack(). If verifier detects out of bounds access under speculative execution from one of the possible paths that includes a truncation, it will reject such program. Given we mask every reg-based pointer arithmetic for unprivileged programs, we've been looking into how it could affect real-world programs in terms of size increase. As the majority of programs are targeted for privileged-only use case, we've unconditionally enabled masking (with its alu restrictions on top of it) for privileged programs for the sake of testing in order to check i) whether they get rejected in its current form, and ii) by how much the number of instructions and size will increase. We've tested this by using Katran, Cilium and test_l4lb from the kernel selftests. For Katran we've evaluated balancer_kern.o, Cilium bpf_lxc.o and an older test object bpf_lxc_opt_-DUNKNOWN.o and l4lb we've used test_l4lb.o as well as test_l4lb_noinline.o. We found that none of the programs got rejected by the verifier with this change, and that impact is rather minimal to none. balancer_kern.o had 13,904 bytes (1,738 insns) xlated and 7,797 bytes JITed before and after the change. Most complex program in bpf_lxc.o had 30,544 bytes (3,817 insns) xlated and 18,538 bytes JITed before and after and none of the other tail call programs in bpf_lxc.o had any changes either. For the older bpf_lxc_opt_-DUNKNOWN.o object we found a small increase from 20,616 bytes (2,576 insns) and 12,536 bytes JITed before to 20,664 bytes (2,582 insns) and 12,558 bytes JITed after the change. Other programs from that object file had similar small increase. Both test_l4lb.o had no change and remained at 6,544 bytes (817 insns) xlated and 3,401 bytes JITed and for test_l4lb_noinline.o constant at 5,080 bytes (634 insns) xlated and 3,313 bytes JITed. This can be explained in that LLVM typically optimizes stack based pointer arithmetic by using K-based operations and that use of dynamic map access is not overly frequent. However, in future we may decide to optimize the algorithm further under known guarantees from branch and value speculation. Latter seems also unclear in terms of prediction heuristics that today's CPUs apply as well as whether there could be collisions in e.g. the predictor's Value History/Pattern Table for triggering out of bounds access, thus masking is performed unconditionally at this point but could be subject to relaxation later on. We were generally also brainstorming various other approaches for mitigation, but the blocker was always lack of available registers at runtime and/or overhead for runtime tracking of limits belonging to a specific pointer. Thus, we found this to be minimally intrusive under given constraints. With that in place, a simple example with sanitized access on unprivileged load at post-verification time looks as follows: # bpftool prog dump xlated id 282 [...] 28: (79) r1 = *(u64 *)(r7 +0) 29: (79) r2 = *(u64 *)(r7 +8) 30: (57) r1 &= 15 31: (79) r3 = *(u64 *)(r0 +4608) 32: (57) r3 &= 1 33: (47) r3 |= 1 34: (2d) if r2 > r3 goto pc+19 35: (b4) (u32) r11 = (u32) 20479 | 36: (1f) r11 -= r2 | Dynamic sanitation for pointer 37: (4f) r11 |= r2 | arithmetic with registers 38: (87) r11 = -r11 | containing bounded or known 39: (c7) r11 s>>= 63 | scalars in order to prevent 40: (5f) r11 &= r2 | out of bounds speculation. 41: (0f) r4 += r11 | 42: (71) r4 = *(u8 *)(r4 +0) 43: (6f) r4 <<= r1 [...] For the case where the scalar sits in the destination register as opposed to the source register, the following code is emitted for the above example: [...] 16: (b4) (u32) r11 = (u32) 20479 17: (1f) r11 -= r2 18: (4f) r11 |= r2 19: (87) r11 = -r11 20: (c7) r11 s>>= 63 21: (5f) r2 &= r11 22: (0f) r2 += r0 23: (61) r0 = *(u32 *)(r2 +0) [...] JIT blinding example with non-conflicting use of r10: [...] d5: je 0x0000000000000106 _ d7: mov 0x0(%rax),%edi | da: mov $0xf153246,%r10d | Index load from map value and e0: xor $0xf153259,%r10 | (const blinded) mask with 0x1f. e7: and %r10,%rdi |_ ea: mov $0x2f,%r10d | f0: sub %rdi,%r10 | Sanitized addition. Both use r10 f3: or %rdi,%r10 | but do not interfere with each f6: neg %r10 | other. (Neither do these instructions f9: sar $0x3f,%r10 | interfere with the use of ax as temp fd: and %r10,%rdi | in interpreter.) 100: add %rax,%rdi |_ 103: mov 0x0(%rdi),%eax [...] Tested that it fixes Jann's reproducer, and also checked that test_verifier and test_progs suite with interpreter, JIT and JIT with hardening enabled on x86-64 and arm64 runs successfully. [0] Speculose: Analyzing the Security Implications of Speculative Execution in CPUs, Giorgi Maisuradze and Christian Rossow, https://arxiv.org/pdf/1801.04084.pdf [1] A Systematic Evaluation of Transient Execution Attacks and Defenses, Claudio Canella, Jo Van Bulck, Michael Schwarz, Moritz Lipp, Benjamin von Berg, Philipp Ortner, Frank Piessens, Dmitry Evtyushkin, Daniel Gruss, https://arxiv.org/pdf/1811.05441.pdf Fixes: b2157399cc98 ("bpf: prevent out-of-bounds speculation") Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
* bpf: fix check_map_access smin_value test when pointer contains offsetDaniel Borkmann2019-01-311-1/+5
| | | | | | | | | | | | | | | | | | | | | [ commit b7137c4eab85c1cf3d46acdde90ce1163b28c873 upstream ] In check_map_access() we probe actual bounds through __check_map_access() with offset of reg->smin_value + off for lower bound and offset of reg->umax_value + off for the upper bound. However, even though the reg->smin_value could have a negative value, the final result of the sum with off could be positive when pointer arithmetic with known and unknown scalars is combined. In this case we reject the program with an error such as "R<x> min value is negative, either use unsigned index or do a if (index >=0) check." even though the access itself would be fine. Therefore extend the check to probe whether the actual resulting reg->smin_value + off is less than zero. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
* bpf: restrict unknown scalars of mixed signed bounds for unprivilegedDaniel Borkmann2019-01-311-1/+7
| | | | | | | | | | | | | | | | | | [ commit 9d7eceede769f90b66cfa06ad5b357140d5141ed upstream ] For unknown scalars of mixed signed bounds, meaning their smin_value is negative and their smax_value is positive, we need to reject arithmetic with pointer to map value. For unprivileged the goal is to mask every map pointer arithmetic and this cannot reliably be done when it is unknown at verification time whether the scalar value is negative or positive. Given this is a corner case, the likelihood of breaking should be very small. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
* bpf: restrict stack pointer arithmetic for unprivilegedDaniel Borkmann2019-01-311-22/+41
| | | | | | | | | | | | | | | | | | [ commit e4298d25830a866cc0f427d4bccb858e76715859 upstream ] Restrict stack pointer arithmetic for unprivileged users in that arithmetic itself must not go out of bounds as opposed to the actual access later on. Therefore after each adjust_ptr_min_max_vals() with a stack pointer as a destination we simulate a check_stack_access() of 1 byte on the destination and once that fails the program is rejected for unprivileged program loads. This is analog to map value pointer arithmetic and needed for masking later on. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
* bpf: restrict map value pointer arithmetic for unprivilegedDaniel Borkmann2019-01-311-0/+11
| | | | | | | | | | | | | | | | | | | | [ commit 0d6303db7970e6f56ae700fa07e11eb510cda125 upstream ] Restrict map value pointer arithmetic for unprivileged users in that arithmetic itself must not go out of bounds as opposed to the actual access later on. Therefore after each adjust_ptr_min_max_vals() with a map value pointer as a destination it will simulate a check_map_access() of 1 byte on the destination and once that fails the program is rejected for unprivileged program loads. We use this later on for masking any pointer arithmetic with the remainder of the map value space. The likelihood of breaking any existing real-world unprivileged eBPF program is very small for this corner case. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
* bpf: enable access to ax register also from verifier rewriteDaniel Borkmann2019-01-311-0/+20
| | | | | | | | | | | | | | | | | | | [ commit 9b73bfdd08e73231d6a90ae6db4b46b3fbf56c30 upstream ] Right now we are using BPF ax register in JIT for constant blinding as well as in interpreter as temporary variable. Verifier will not be able to use it simply because its use will get overridden from the former in bpf_jit_blind_insn(). However, it can be made to work in that blinding will be skipped if there is prior use in either source or destination register on the instruction. Taking constraints of ax into account, the verifier is then open to use it in rewrites under some constraints. Note, ax register already has mappings in every eBPF JIT. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
* bpf: move tmp variable into ax register in interpreterDaniel Borkmann2019-01-311-17/+17
| | | | | | | | | | | | | | | | | [ commit 144cd91c4c2bced6eb8a7e25e590f6618a11e854 upstream ] This change moves the on-stack 64 bit tmp variable in ___bpf_prog_run() into the hidden ax register. The latter is currently only used in JITs for constant blinding as a temporary scratch register, meaning the BPF interpreter will never see the use of ax. Therefore it is safe to use it for the cases where tmp has been used earlier. This is needed to later on allow restricted hidden use of ax in both interpreter and JITs. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
* bpf: move {prev_,}insn_idx into verifier envDaniel Borkmann2019-01-311-37/+38
| | | | | | | | | | | | | | | | | [ commit c08435ec7f2bc8f4109401f696fd55159b4b40cb upstream ] Move prev_insn_idx and insn_idx from the do_check() function into the verifier environment, so they can be read inside the various helper functions for handling the instructions. It's easier to put this into the environment rather than changing all call-sites only to pass it along. insn_idx is useful in particular since this later on allows to hold state in env->insn_aux_data[env->insn_idx]. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
* bpf: add per-insn complexity limitAlexei Starovoitov2019-01-311-1/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ commit ceefbc96fa5c5b975d87bf8e89ba8416f6b764d9 upstream ] malicious bpf program may try to force the verifier to remember a lot of distinct verifier states. Put a limit to number of per-insn 'struct bpf_verifier_state'. Note that hitting the limit doesn't reject the program. It potentially makes the verifier do more steps to analyze the program. It means that malicious programs will hit BPF_COMPLEXITY_LIMIT_INSNS sooner instead of spending cpu time walking long link list. The limit of BPF_COMPLEXITY_LIMIT_STATES==64 affects cilium progs with slight increase in number of "steps" it takes to successfully verify the programs: before after bpf_lb-DLB_L3.o 1940 1940 bpf_lb-DLB_L4.o 3089 3089 bpf_lb-DUNKNOWN.o 1065 1065 bpf_lxc-DDROP_ALL.o 28052 | 28162 bpf_lxc-DUNKNOWN.o 35487 | 35541 bpf_netdev.o 10864 10864 bpf_overlay.o 6643 6643 bpf_lcx_jit.o 38437 38437 But it also makes malicious program to be rejected in 0.4 seconds vs 6.5 Hence apply this limit to unprivileged programs only. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Edward Cree <ecree@solarflare.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
* bpf: improve verifier branch analysisAlexei Starovoitov2019-01-311-13/+80
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ commit 4f7b3e82589e0de723780198ec7983e427144c0a upstream ] pathological bpf programs may try to force verifier to explode in the number of branch states: 20: (d5) if r1 s<= 0x24000028 goto pc+0 21: (b5) if r0 <= 0xe1fa20 goto pc+2 22: (d5) if r1 s<= 0x7e goto pc+0 23: (b5) if r0 <= 0xe880e000 goto pc+0 24: (c5) if r0 s< 0x2100ecf4 goto pc+0 25: (d5) if r1 s<= 0xe880e000 goto pc+1 26: (c5) if r0 s< 0xf4041810 goto pc+0 27: (d5) if r1 s<= 0x1e007e goto pc+0 28: (b5) if r0 <= 0xe86be000 goto pc+0 29: (07) r0 += 16614 30: (c5) if r0 s< 0x6d0020da goto pc+0 31: (35) if r0 >= 0x2100ecf4 goto pc+0 Teach verifier to recognize always taken and always not taken branches. This analysis is already done for == and != comparison. Expand it to all other branches. It also helps real bpf programs to be verified faster: before after bpf_lb-DLB_L3.o 2003 1940 bpf_lb-DLB_L4.o 3173 3089 bpf_lb-DUNKNOWN.o 1080 1065 bpf_lxc-DDROP_ALL.o 29584 28052 bpf_lxc-DUNKNOWN.o 36916 35487 bpf_netdev.o 11188 10864 bpf_overlay.o 6679 6643 bpf_lcx_jit.o 39555 38437 Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Edward Cree <ecree@solarflare.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
* posix-cpu-timers: Unbreak timer rearmingThomas Gleixner2019-01-311-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 93ad0fc088c5b4631f796c995bdd27a082ef33a6 upstream. The recent commit which prevented a division by 0 issue in the alarm timer code broke posix CPU timers as an unwanted side effect. The reason is that the common rearm code checks for timer->it_interval being 0 now. What went unnoticed is that the posix cpu timer setup does not initialize timer->it_interval as it stores the interval in CPU timer specific storage. The reason for the separate storage is historical as the posix CPU timers always had a 64bit nanoseconds representation internally while timer->it_interval is type ktime_t which used to be a modified timespec representation on 32bit machines. Instead of reverting the offending commit and fixing the alarmtimer issue in the alarmtimer code, store the interval in timer->it_interval at CPU timer setup time so the common code check works. This also repairs the existing inconistency of the posix CPU timer code which kept a single shot timer armed despite of the interval being 0. The separate storage can be removed in mainline, but that needs to be a separate commit as the current one has to be backported to stable kernels. Fixes: 0e334db6bb4b ("posix-timers: Fix division by zero bug") Reported-by: H.J. Lu <hjl.tools@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <john.stultz@linaro.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20190111133500.840117406@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* bpf: relax verifier restriction on BPF_MOV | BPF_ALUJiong Wang2019-01-261-4/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit e434b8cdf788568ba65a0a0fd9f3cb41f3ca1803 ] Currently, the destination register is marked as unknown for 32-bit sub-register move (BPF_MOV | BPF_ALU) whenever the source register type is SCALAR_VALUE. This is too conservative that some valid cases will be rejected. Especially, this may turn a constant scalar value into unknown value that could break some assumptions of verifier. For example, test_l4lb_noinline.c has the following C code: struct real_definition *dst 1: if (!get_packet_dst(&dst, &pckt, vip_info, is_ipv6)) 2: return TC_ACT_SHOT; 3: 4: if (dst->flags & F_IPV6) { get_packet_dst is responsible for initializing "dst" into valid pointer and return true (1), otherwise return false (0). The compiled instruction sequence using alu32 will be: 412: (54) (u32) r7 &= (u32) 1 413: (bc) (u32) r0 = (u32) r7 414: (95) exit insn 413, a BPF_MOV | BPF_ALU, however will turn r0 into unknown value even r7 contains SCALAR_VALUE 1. This causes trouble when verifier is walking the code path that hasn't initialized "dst" inside get_packet_dst, for which case 0 is returned and we would then expect verifier concluding line 1 in the above C code pass the "if" check, therefore would skip fall through path starting at line 4. Now, because r0 returned from callee has became unknown value, so verifier won't skip analyzing path starting at line 4 and "dst->flags" requires dereferencing the pointer "dst" which actually hasn't be initialized for this path. This patch relaxed the code marking sub-register move destination. For a SCALAR_VALUE, it is safe to just copy the value from source then truncate it into 32-bit. A unit test also included to demonstrate this issue. This test will fail before this patch. This relaxation could let verifier skipping more paths for conditional comparison against immediate. It also let verifier recording a more accurate/strict value for one register at one state, if this state end up with going through exit without rejection and it is used for state comparison later, then it is possible an inaccurate/permissive value is better. So the real impact on verifier processed insn number is complex. But in all, without this fix, valid program could be rejected. >From real benchmarking on kernel selftests and Cilium bpf tests, there is no impact on processed instruction number when tests ares compiled with default compilation options. There is slightly improvements when they are compiled with -mattr=+alu32 after this patch. Also, test_xdp_noinline/-mattr=+alu32 now passed verification. It is rejected before this fix. Insn processed before/after this patch: default -mattr=+alu32 Kernel selftest === test_xdp.o 371/371 369/369 test_l4lb.o 6345/6345 5623/5623 test_xdp_noinline.o 2971/2971 rejected/2727 test_tcp_estates.o 429/429 430/430 Cilium bpf === bpf_lb-DLB_L3.o: 2085/2085 1685/1687 bpf_lb-DLB_L4.o: 2287/2287 1986/1982 bpf_lb-DUNKNOWN.o: 690/690 622/622 bpf_lxc.o: 95033/95033 N/A bpf_netdev.o: 7245/7245 N/A bpf_overlay.o: 2898/2898 3085/2947 NOTE: - bpf_lxc.o and bpf_netdev.o compiled by -mattr=+alu32 are rejected by verifier due to another issue inside verifier on supporting alu32 binary. - Each cilium bpf program could generate several processed insn number, above number is sum of them. v1->v2: - Restrict the change on SCALAR_VALUE. - Update benchmark numbers on Cilium bpf tests. Signed-off-by: Jiong Wang <jiong.wang@netronome.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* bpf: Allow narrow loads with offset > 0Andrey Ignatov2019-01-261-5/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [ Upstream commit 46f53a65d2de3e1591636c22b626b09d8684fd71 ] Currently BPF verifier allows narrow loads for a context field only with offset zero. E.g. if there is a __u32 field then only the following loads are permitted: * off=0, size=1 (narrow); * off=0, size=2 (narrow); * off=0, size=4 (full). On the other hand LLVM can generate a load with offset different than zero that make sense from program logic point of view, but verifier doesn't accept it. E.g. tools/testing/selftests/bpf/sendmsg4_prog.c has code: #define DST_IP4 0xC0A801FEU /* 192.168.1.254 */ ... if ((ctx->user_ip4 >> 24) == (bpf_htonl(DST_IP4) >> 24) && where ctx is struct bpf_sock_addr. Some versions of LLVM can produce the following byte code for it: 8: 71 12 07 00 00 00 00 00 r2 = *(u8 *)(r1 + 7) 9: 67 02 00 00 18 00 00 00 r2 <<= 24 10: 18 03 00 00 00 00 00 fe 00 00 00 00 00 00 00 00 r3 = 4261412864 ll 12: 5d 32 07 00 00 00 00 00 if r2 != r3 goto +7 <LBB0_6> where `*(u8 *)(r1 + 7)` means narrow load for ctx->user_ip4 with size=1 and offset=3 (7 - sizeof(ctx->user_family) = 3). This load is currently rejected by verifier. Verifier code that rejects such loads is in bpf_ctx_narrow_access_ok() what means any is_valid_access implementation, that uses the function, works this way, e.g. bpf_skb_is_valid_access() for __sk_buff or sock_addr_is_valid_access() for bpf_sock_addr. The patch makes such loads supported. Offset can be in [0; size_default) but has to be multiple of load size. E.g. for __u32 field the following loads are supported now: * off=0, size=1 (narrow); * off=1, size=1 (narrow); * off=2, size=1 (narrow); * off=3, size=1 (narrow); * off=0, size=2 (narrow); * off=2, size=2 (narrow); * off=0, size=4 (full). Reported-by: Yonghong Song <yhs@fb.com> Signed-off-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
* sched/fair: Fix infinite loop in update_blocked_averages() by reverting ↵Linus Torvalds2019-01-131-34/+9Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | a9e7f6544b9c commit c40f7d74c741a907cfaeb73a7697081881c497d0 upstream. Zhipeng Xie, Xie XiuQi and Sargun Dhillon reported lockups in the scheduler under high loads, starting at around the v4.18 time frame, and Zhipeng Xie tracked it down to bugs in the rq->leaf_cfs_rq_list manipulation. Do a (manual) revert of: a9e7f6544b9c ("sched/fair: Fix O(nr_cgroups) in load balance path") It turns out that the list_del_leaf_cfs_rq() introduced by this commit is a surprising property that was not considered in followup commits such as: 9c2791f936ef ("sched/fair: Fix hierarchical order in rq->leaf_cfs_rq_list") As Vincent Guittot explains: "I think that there is a bigger problem with commit a9e7f6544b9c and cfs_rq throttling: Let take the example of the following topology TG2 --> TG1 --> root: 1) The 1st time a task is enqueued, we will add TG2 cfs_rq then TG1 cfs_rq to leaf_cfs_rq_list and we are sure to do the whole branch in one path because it has never been used and can't be throttled so tmp_alone_branch will point to leaf_cfs_rq_list at the end. 2) Then TG1 is throttled 3) and we add TG3 as a new child of TG1. 4) The 1st enqueue of a task on TG3 will add TG3 cfs_rq just before TG1 cfs_rq and tmp_alone_branch will stay on rq->leaf_cfs_rq_list. With commit a9e7f6544b9c, we can del a cfs_rq from rq->leaf_cfs_rq_list. So if the load of TG1 cfs_rq becomes NULL before step 2) above, TG1 cfs_rq is removed from the list. Then at step 4), TG3 cfs_rq is added at the beginning of rq->leaf_cfs_rq_list but tmp_alone_branch still points to TG3 cfs_rq because its throttled parent can't be enqueued when the lock is released. tmp_alone_branch doesn't point to rq->leaf_cfs_rq_list whereas it should. So if TG3 cfs_rq is removed or destroyed before tmp_alone_branch points on another TG cfs_rq, the next TG cfs_rq that will be added, will be linked outside rq->leaf_cfs_rq_list - which is bad. In addition, we can break the ordering of the cfs_rq in rq->leaf_cfs_rq_list but this ordering is used to update and propagate the update from leaf down to root." Instead of trying to work through all these cases and trying to reproduce the very high loads that produced the lockup to begin with, simplify the code temporarily by reverting a9e7f6544b9c - which change was clearly not thought through completely. This (hopefully) gives us a kernel that doesn't lock up so people can continue to enjoy their holidays without worrying about regressions. ;-) [ mingo: Wrote changelog, fixed weird spelling in code comment while at it. ] Analyzed-by: Xie XiuQi <xiexiuqi@huawei.com> Analyzed-by: Vincent Guittot <vincent.guittot@linaro.org> Reported-by: Zhipeng Xie <xiezhipeng1@huawei.com> Reported-by: Sargun Dhillon <sargun@sargun.me> Reported-by: Xie XiuQi <xiexiuqi@huawei.com> Tested-by: Zhipeng Xie <xiezhipeng1@huawei.com> Tested-by: Sargun Dhillon <sargun@sargun.me> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Acked-by: Vincent Guittot <vincent.guittot@linaro.org> Cc: <stable@vger.kernel.org> # v4.13+ Cc: Bin Li <huawei.libin@huawei.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: a9e7f6544b9c ("sched/fair: Fix O(nr_cgroups) in load balance path") Link: http://lkml.kernel.org/r/1545879866-27809-1-git-send-email-xiexiuqi@huawei.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* Fix failure path in alloc_pid()Matthew Wilcox2019-01-131-2/+4
| | | | | | | | | | | | | | | | | commit 1a80dade010c7a7f4885a4c4c2a7ac22cc7b34df upstream. The failure path removes the allocated PIDs from the wrong namespace. This could lead to us inadvertently reusing PIDs in the leaf namespace and leaking PIDs in parent namespaces. Fixes: 95846ecf9dac ("pid: replace pid bitmap implementation with IDR API") Cc: <stable@vger.kernel.org> Signed-off-by: Matthew Wilcox <willy@infradead.org> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* srcu: Lock srcu_data structure in srcu_gp_start()Dennis Krein2019-01-131-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | commit eb4c2382272ae7ae5d81fdfa5b7a6c86146eaaa4 upstream. The srcu_gp_start() function is called with the srcu_struct structure's ->lock held, but not with the srcu_data structure's ->lock. This is problematic because this function accesses and updates the srcu_data structure's ->srcu_cblist, which is protected by that lock. Failing to hold this lock can result in corruption of the SRCU callback lists, which in turn can result in arbitrarily bad results. This commit therefore makes srcu_gp_start() acquire the srcu_data structure's ->lock across the calls to rcu_segcblist_advance() and rcu_segcblist_accelerate(), thus preventing this corruption. Reported-by: Bart Van Assche <bvanassche@acm.org> Reported-by: Christoph Hellwig <hch@infradead.org> Reported-by: Sebastian Kuzminsky <seb.kuzminsky@gmail.com> Signed-off-by: Dennis Krein <Dennis.Krein@netapp.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Tested-by: Dennis Krein <Dennis.Krein@netapp.com> Cc: <stable@vger.kernel.org> # 4.16.x Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* dma-direct: do not include SME mask in the DMA supported checkLendacky, Thomas2019-01-131-2/+11
| | | | | | | | | | | | | | | | | | | | | commit c92a54cfa0257e8ffd66b2a17d49e9c0bd4b769f upstream. The dma_direct_supported() function intends to check the DMA mask against specific values. However, the phys_to_dma() function includes the SME encryption mask, which defeats the intended purpose of the check. This results in drivers that support less than 48-bit DMA (SME encryption mask is bit 47) from being able to set the DMA mask successfully when SME is active, which results in the driver failing to initialize. Change the function used to check the mask from phys_to_dma() to __phys_to_dma() so that the SME encryption mask is not part of the check. Fixes: c1d0af1a1d5d ("kernel/dma/direct: take DMA offset into account in dma_direct_supported") Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* mm, devm_memremap_pages: add MEMORY_DEVICE_PRIVATE supportDan Williams2019-01-131-12/+41
| | | | | | | | | | | | | | | | | | | | | | | commit 69324b8f48339de2f90fdf2f774687fc6c47629a upstream. In preparation for consolidating all ZONE_DEVICE enabling via devm_memremap_pages(), teach it how to handle the constraints of MEMORY_DEVICE_PRIVATE ranges. [jglisse@redhat.com: call move_pfn_range_to_zone for MEMORY_DEVICE_PRIVATE] Link: http://lkml.kernel.org/r/154275559036.76910.12434636179931292607.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Jérôme Glisse <jglisse@redhat.com> Acked-by: Christoph Hellwig <hch@lst.de> Reported-by: Logan Gunthorpe <logang@deltatee.com> Reviewed-by: Logan Gunthorpe <logang@deltatee.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* mm, devm_memremap_pages: fix shutdown handlingDan Williams2019-01-131-16/+15Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit a95c90f1e2c253b280385ecf3d4ebfe476926b28 upstream. The last step before devm_memremap_pages() returns success is to allocate a release action, devm_memremap_pages_release(), to tear the entire setup down. However, the result from devm_add_action() is not checked. Checking the error from devm_add_action() is not enough. The api currently relies on the fact that the percpu_ref it is using is killed by the time the devm_memremap_pages_release() is run. Rather than continue this awkward situation, offload the responsibility of killing the percpu_ref to devm_memremap_pages_release() directly. This allows devm_memremap_pages() to do the right thing relative to init failures and shutdown. Without this change we could fail to register the teardown of devm_memremap_pages(). The likelihood of hitting this failure is tiny as small memory allocations almost always succeed. However, the impact of the failure is large given any future reconfiguration, or disable/enable, of an nvdimm namespace will fail forever as subsequent calls to devm_memremap_pages() will fail to setup the pgmap_radix since there will be stale entries for the physical address range. An argument could be made to require that the ->kill() operation be set in the @pgmap arg rather than passed in separately. However, it helps code readability, tracking the lifetime of a given instance, to be able to grep the kill routine directly at the devm_memremap_pages() call site. Link: http://lkml.kernel.org/r/154275558526.76910.7535251937849268605.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com> Fixes: e8d513483300 ("memremap: change devm_memremap_pages interface...") Reviewed-by: "Jérôme Glisse" <jglisse@redhat.com> Reported-by: Logan Gunthorpe <logang@deltatee.com> Reviewed-by: Logan Gunthorpe <logang@deltatee.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* mm, devm_memremap_pages: kill mapping "System RAM" supportDan Williams2019-01-131-6/+3Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 06489cfbd915ff36c8e36df27f1c2dc60f97ca56 upstream. Given the fact that devm_memremap_pages() requires a percpu_ref that is torn down by devm_memremap_pages_release() the current support for mapping RAM is broken. Support for remapping "System RAM" has been broken since the beginning and there is no existing user of this this code path, so just kill the support and make it an explicit error. This cleanup also simplifies a follow-on patch to fix the error path when setting a devm release action for devm_memremap_pages_release() fails. Link: http://lkml.kernel.org/r/154275557997.76910.14689813630968180480.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: "Jérôme Glisse" <jglisse@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Logan Gunthorpe <logang@deltatee.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* mm, devm_memremap_pages: mark devm_memremap_pages() EXPORT_SYMBOL_GPLDan Williams2019-01-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 808153e1187fa77ac7d7dad261ff476888dcf398 upstream. devm_memremap_pages() is a facility that can create struct page entries for any arbitrary range and give drivers the ability to subvert core aspects of page management. Specifically the facility is tightly integrated with the kernel's memory hotplug functionality. It injects an altmap argument deep into the architecture specific vmemmap implementation to allow allocating from specific reserved pages, and it has Linux specific assumptions about page structure reference counting relative to get_user_pages() and get_user_pages_fast(). It was an oversight and a mistake that this was not marked EXPORT_SYMBOL_GPL from the outset. Again, devm_memremap_pagex() exposes and relies upon core kernel internal assumptions and will continue to evolve along with 'struct page', memory hotplug, and support for new memory types / topologies. Only an in-kernel GPL-only driver is expected to keep up with this ongoing evolution. This interface, and functionality derived from this interface, is not suitable for kernel-external drivers. Link: http://lkml.kernel.org/r/154275557457.76910.16923571232582744134.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Acked-by: Michal Hocko <mhocko@suse.com> Cc: "Jérôme Glisse" <jglisse@redhat.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Logan Gunthorpe <logang@deltatee.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* fork: record start_time lateDavid Herrmann2019-01-131-2/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 7b55851367136b1efd84d98fea81ba57a98304cf upstream. This changes the fork(2) syscall to record the process start_time after initializing the basic task structure but still before making the new process visible to user-space. Technically, we could record the start_time anytime during fork(2). But this might lead to scenarios where a start_time is recorded long before a process becomes visible to user-space. For instance, with userfaultfd(2) and TLS, user-space can delay the execution of fork(2) for an indefinite amount of time (and will, if this causes network access, or similar). By recording the start_time late, it much closer reflects the point in time where the process becomes live and can be observed by other processes. Lastly, this makes it much harder for user-space to predict and control the start_time they get assigned. Previously, user-space could fork a process and stall it in copy_thread_tls() before its pid is allocated, but after its start_time is recorded. This can be misused to later-on cycle through PIDs and resume the stalled fork(2) yielding a process that has the same pid and start_time as a process that existed before. This can be used to circumvent security systems that identify processes by their pid+start_time combination. Even though user-space was always aware that start_time recording is flaky (but several projects are known to still rely on start_time-based identification), changing the start_time to be recorded late will help mitigate existing attacks and make it much harder for user-space to control the start_time a process gets assigned. Reported-by: Jann Horn <jannh@google.com> Signed-off-by: Tom Gundersen <teg@jklm.no> Signed-off-by: David Herrmann <dh.herrmann@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* cgroup: fix CSS_TASK_ITER_PROCSTejun Heo2019-01-091-12/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit e9d81a1bc2c48ea9782e3e8b53875f419766ef47 upstream. CSS_TASK_ITER_PROCS implements process-only iteration by making css_task_iter_advance() skip tasks which aren't threadgroup leaders; however, when an iteration is started css_task_iter_start() calls the inner helper function css_task_iter_advance_css_set() instead of css_task_iter_advance(). As the helper doesn't have the skip logic, when the first task to visit is a non-leader thread, it doesn't get skipped correctly as shown in the following example. # ps -L 2030 PID LWP TTY STAT TIME COMMAND 2030 2030 pts/0 Sl+ 0:00 ./test-thread 2030 2031 pts/0 Sl+ 0:00 ./test-thread # mkdir -p /sys/fs/cgroup/x/a/b # echo threaded > /sys/fs/cgroup/x/a/cgroup.type # echo threaded > /sys/fs/cgroup/x/a/b/cgroup.type # echo 2030 > /sys/fs/cgroup/x/a/cgroup.procs # cat /sys/fs/cgroup/x/a/cgroup.threads 2030 2031 # cat /sys/fs/cgroup/x/cgroup.procs 2030 # echo 2030 > /sys/fs/cgroup/x/a/b/cgroup.threads # cat /sys/fs/cgroup/x/cgroup.procs 2031 2030 The last read of cgroup.procs is incorrectly showing non-leader 2031 in cgroup.procs output. This can be fixed by updating css_task_iter_advance() to handle the first advance and css_task_iters_tart() to call css_task_iter_advance() instead of the inner helper. After the fix, the same commands result in the following (correct) result: # ps -L 2062 PID LWP TTY STAT TIME COMMAND 2062 2062 pts/0 Sl+ 0:00 ./test-thread 2062 2063 pts/0 Sl+ 0:00 ./test-thread # mkdir -p /sys/fs/cgroup/x/a/b # echo threaded > /sys/fs/cgroup/x/a/cgroup.type # echo threaded > /sys/fs/cgroup/x/a/b/cgroup.type # echo 2062 > /sys/fs/cgroup/x/a/cgroup.procs # cat /sys/fs/cgroup/x/a/cgroup.threads 2062 2063 # cat /sys/fs/cgroup/x/cgroup.procs 2062 # echo 2062 > /sys/fs/cgroup/x/a/b/cgroup.threads # cat /sys/fs/cgroup/x/cgroup.procs 2062 Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> Fixes: 8cfd8147df67 ("cgroup: implement cgroup v2 thread support") Cc: stable@vger.kernel.org # v4.14+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* panic: avoid deadlocks in re-entrant console driversSergey Senozhatsky2018-12-291-1/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit c7c3f05e341a9a2bd1a92993d4f996cfd6e7348e upstream. From printk()/serial console point of view panic() is special, because it may force CPU to re-enter printk() or/and serial console driver. Therefore, some of serial consoles drivers are re-entrant. E.g. 8250: serial8250_console_write() { if (port->sysrq) locked = 0; else if (oops_in_progress) locked = spin_trylock_irqsave(&port->lock, flags); else spin_lock_irqsave(&port->lock, flags); ... } panic() does set oops_in_progress via bust_spinlocks(1), so in theory we should be able to re-enter serial console driver from panic(): CPU0 <NMI> uart_console_write() serial8250_console_write() // if (oops_in_progress) // spin_trylock_irqsave() call_console_drivers() console_unlock() console_flush_on_panic() bust_spinlocks(1) // oops_in_progress++ panic() <NMI/> spin_lock_irqsave(&port->lock, flags) // spin_lock_irqsave() serial8250_console_write() call_console_drivers() console_unlock() printk() ... However, this does not happen and we deadlock in serial console on port->lock spinlock. And the problem is that console_flush_on_panic() called after bust_spinlocks(0): void panic(const char *fmt, ...) { bust_spinlocks(1); ... bust_spinlocks(0); console_flush_on_panic(); ... } bust_spinlocks(0) decrements oops_in_progress, so oops_in_progress can go back to zero. Thus even re-entrant console drivers will simply spin on port->lock spinlock. Given that port->lock may already be locked either by a stopped CPU, or by the very same CPU we execute panic() on (for instance, NMI panic() on printing CPU) the system deadlocks and does not reboot. Fix this by removing bust_spinlocks(0), so oops_in_progress is always set in panic() now and, thus, re-entrant console drivers will trylock the port->lock instead of spinning on it forever, when we call them from console_flush_on_panic(). Link: http://lkml.kernel.org/r/20181025101036.6823-1-sergey.senozhatsky@gmail.com Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Daniel Wang <wonderfly@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Cc: Jiri Slaby <jslaby@suse.com> Cc: Peter Feiner <pfeiner@google.com> Cc: linux-serial@vger.kernel.org Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: stable@vger.kernel.org Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* futex: Cure exit raceThomas Gleixner2018-12-291-6/+63
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit da791a667536bf8322042e38ca85d55a78d3c273 upstream. Stefan reported, that the glibc tst-robustpi4 test case fails occasionally. That case creates the following race between sys_exit() and sys_futex_lock_pi(): CPU0 CPU1 sys_exit() sys_futex() do_exit() futex_lock_pi() exit_signals(tsk) No waiters: tsk->flags |= PF_EXITING; *uaddr == 0x00000PID mm_release(tsk) Set waiter bit exit_robust_list(tsk) { *uaddr = 0x80000PID; Set owner died attach_to_pi_owner() { *uaddr = 0xC0000000; tsk = get_task(PID); } if (!tsk->flags & PF_EXITING) { ... attach(); tsk->flags |= PF_EXITPIDONE; } else { if (!(tsk->flags & PF_EXITPIDONE)) return -EAGAIN; return -ESRCH; <--- FAIL } ESRCH is returned all the way to user space, which triggers the glibc test case assert. Returning ESRCH unconditionally is wrong here because the user space value has been changed by the exiting task to 0xC0000000, i.e. the FUTEX_OWNER_DIED bit is set and the futex PID value has been cleared. This is a valid state and the kernel has to handle it, i.e. taking the futex. Cure it by rereading the user space value when PF_EXITING and PF_EXITPIDONE is set in the task which 'owns' the futex. If the value has changed, let the kernel retry the operation, which includes all regular sanity checks and correctly handles the FUTEX_OWNER_DIED case. If it hasn't changed, then return ESRCH as there is no way to distinguish this case from malfunctioning user space. This happens when the exiting task did not have a robust list, the robust list was corrupted or the user space value in the futex was simply bogus. Reported-by: Stefan Liebler <stli@linux.ibm.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Darren Hart <dvhart@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Sasha Levin <sashal@kernel.org> Cc: stable@vger.kernel.org Link: https://bugzilla.kernel.org/show_bug.cgi?id=200467 Link: https://lkml.kernel.org/r/20181210152311.986181245@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* posix-timers: Fix division by zero bugThomas Gleixner2018-12-291-4/+1Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 0e334db6bb4b1fd1e2d72c1f3d8f004313cd9f94 upstream. The signal delivery path of posix-timers can try to rearm the timer even if the interval is zero. That's handled for the common case (hrtimer) but not for alarm timers. In that case the forwarding function raises a division by zero exception. The handling for hrtimer based posix timers is wrong because it marks the timer as active despite the fact that it is stopped. Move the check from common_hrtimer_rearm() to posixtimer_rearm() to cure both issues. Reported-by: syzbot+9d38bedac9cc77b8ad5e@syzkaller.appspotmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <john.stultz@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: sboyd@kernel.org Cc: stable@vger.kernel.org Cc: syzkaller-bugs@googlegroups.com Link: http://lkml.kernel.org/r/alpine.DEB.2.21.1812171328050.1880@nanos.tec.linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* bpf: check pending signals while verifying programsAlexei Starovoitov2018-12-211-0/+3
| | | | | | | | | | | | | | | | | [ Upstream commit c3494801cd1785e2c25f1a5735fa19ddcf9665da ] Malicious user space may try to force the verifier to use as much cpu time and memory as possible. Hence check for pending signals while verifying the program. Note that suspend of sys_bpf(PROG_LOAD) syscall will lead to EAGAIN, since the kernel has to release the resources used for program verification. Reported-by: Anatoly Trosinenko <anatoly.trosinenko@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Edward Cree <ecree@solarflare.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Sasha Levin <sashal@kernel.org>
* locking/qspinlock, x86: Provide liveness guaranteePeter Zijlstra2018-12-211-1/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | commit 7aa54be2976550f17c11a1c3e3630002dea39303 upstream. On x86 we cannot do fetch_or() with a single instruction and thus end up using a cmpxchg loop, this reduces determinism. Replace the fetch_or() with a composite operation: tas-pending + load. Using two instructions of course opens a window we previously did not have. Consider the scenario: CPU0 CPU1 CPU2 1) lock trylock -> (0,0,1) 2) lock trylock /* fail */ 3) unlock -> (0,0,0) 4) lock trylock -> (0,0,1) 5) tas-pending -> (0,1,1) load-val <- (0,1,0) from 3 6) clear-pending-set-locked -> (0,0,1) FAIL: _2_ owners where 5) is our new composite operation. When we consider each part of the qspinlock state as a separate variable (as we can when _Q_PENDING_BITS == 8) then the above is entirely possible, because tas-pending will only RmW the pending byte, so the later load is able to observe prior tail and lock state (but not earlier than its own trylock, which operates on the whole word, due to coherence). To avoid this we need 2 things: - the load must come after the tas-pending (obviously, otherwise it can trivially observe prior state). - the tas-pending must be a full word RmW instruction, it cannot be an XCHGB for example, such that we cannot observe other state prior to setting pending. On x86 we can realize this by using "LOCK BTS m32, r32" for tas-pending followed by a regular load. Note that observing later state is not a problem: - if we fail to observe a later unlock, we'll simply spin-wait for that store to become visible. - if we observe a later xchg_tail(), there is no difference from that xchg_tail() having taken place before the tas-pending. Suggested-by: Will Deacon <will.deacon@arm.com> Reported-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Will Deacon <will.deacon@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: andrea.parri@amarulasolutions.com Cc: longman@redhat.com Fixes: 59fb586b4a07 ("locking/qspinlock: Remove unbounded cmpxchg() loop from locking slowpath") Link: https://lkml.kernel.org/r/20181003130957.183726335@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org> [bigeasy: GEN_BINARY_RMWcc macro redo] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
* locking/qspinlock: Re-order codePeter Zijlstra2018-12-211-29/+27Star
| | | | | | | | | | | | | | | | | | | | commit 53bf57fab7321fb42b703056a4c80fc9d986d170 upstream. Flip the branch condition after atomic_fetch_or_acquire(_Q_PENDING_VAL) such that we loose the indent. This also result in a more natural code flow IMO. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Will Deacon <will.deacon@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: andrea.parri@amarulasolutions.com Cc: longman@redhat.com Link: https://lkml.kernel.org/r/20181003130257.156322446@infradead.org Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Sasha Levin <sashal@kernel.org>
* tracing: Fix memory leak of instance function hash filtersSteven Rostedt (VMware)2018-12-191-0/+1
| | | | | | | | | | | | | | | | | | | | | | | commit 2840f84f74035e5a535959d5f17269c69fa6edc5 upstream. The following commands will cause a memory leak: # cd /sys/kernel/tracing # mkdir instances/foo # echo schedule > instance/foo/set_ftrace_filter # rmdir instances/foo The reason is that the hashes that hold the filters to set_ftrace_filter and set_ftrace_notrace are not freed if they contain any data on the instance and the instance is removed. Found by kmemleak detector. Cc: stable@vger.kernel.org Fixes: 591dffdade9f ("ftrace: Allow for function tracing instance to filter functions") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing: Fix memory leak in set_trigger_filter()Steven Rostedt (VMware)2018-12-191-2/+4
| | | | | | | | | | | | | | | | | | | | | | commit 3cec638b3d793b7cacdec5b8072364b41caeb0e1 upstream. When create_event_filter() fails in set_trigger_filter(), the filter may still be allocated and needs to be freed. The caller expects the data->filter to be updated with the new filter, even if the new filter failed (we could add an error message by setting set_str parameter of create_event_filter(), but that's another update). But because the error would just exit, filter was left hanging and nothing could free it. Found by kmemleak detector. Cc: stable@vger.kernel.org Fixes: bac5fb97a173a ("tracing: Add and use generic set_trigger_filter() implementation") Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* tracing: Fix memory leak in create_filter()Steven Rostedt (VMware)2018-12-191-1/+4
| | | | | | | | | | | | | | | | | | | commit b61c19209c2c35ea2a2fe502d484703686eba98c upstream. The create_filter() calls create_filter_start() which allocates a "parse_error" descriptor, but fails to call create_filter_finish() that frees it. The op_stack and inverts in predicate_parse() were also not freed. Found by kmemleak detector. Cc: stable@vger.kernel.org Fixes: 80765597bc587 ("tracing: Rewrite filter logic to be simpler and faster") Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>