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| author | Vincent Fazio | 2021-01-31 07:19:48 +0100 |
|---|---|---|
| committer | Laurent Vivier | 2021-03-13 10:45:11 +0100 |
| commit | 0266e8e3b3981b492e82be20bb97e8ed9792ed00 (patch) | |
| tree | db718fb4ce62fe75ff6b2872dc4f6e430c6780ef | |
| parent | linux-user/elfload: do not assume MAP_FIXED_NOREPLACE kernel support (diff) | |
| download | qemu-0266e8e3b3981b492e82be20bb97e8ed9792ed00.tar.gz qemu-0266e8e3b3981b492e82be20bb97e8ed9792ed00.tar.xz qemu-0266e8e3b3981b492e82be20bb97e8ed9792ed00.zip | |
linux-user/elfload: fix address calculation in fallback scenario
Previously, guest_loaddr was not taken into account when returning an
address from pgb_find_hole when /proc/self/maps was unavailable which
caused an improper guest_base address to be calculated.
This could cause a SIGSEGV later in load_elf_image -> target_mmap for
ET_EXEC type images since the mmap MAP_FIXED flag is specified which
could clobber existing mappings at the address returnd by g2h().
mmap(0xd87000, 16846912, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE|0x100000, -1, 0) = 0xd87000
munmap(0xd87000, 16846912) = 0
write(2, "Locating guest address space @ 0"..., 40Locating guest address space @ 0xd87000) = 40
mmap(0x1187000, 16850944, PROT_NONE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = 0x1187000
--- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_ACCERR, si_addr=0x2188310} ---
+++ killed by SIGSEGV +++
Now, pgd_find_hole accounts for guest_loaddr in this scenario.
Fixes: ad592e37dfcc ("linux-user: provide fallback pgd_find_hole for bare chroots")
Signed-off-by: Vincent Fazio <vfazio@gmail.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20210131061948.15990-1-vfazio@xes-inc.com>
[lv: updated it to check if ret == -1]
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
| -rw-r--r-- | linux-user/elfload.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/linux-user/elfload.c b/linux-user/elfload.c index e525901659..c6731013fd 100644 --- a/linux-user/elfload.c +++ b/linux-user/elfload.c @@ -2235,7 +2235,8 @@ static uintptr_t pgb_find_hole(uintptr_t guest_loaddr, uintptr_t guest_size, brk = (uintptr_t)sbrk(0); if (!maps) { - return pgd_find_hole_fallback(guest_size, brk, align, offset); + ret = pgd_find_hole_fallback(guest_size, brk, align, offset); + return ret == -1 ? -1 : ret - guest_loaddr; } /* The first hole is before the first map entry. */ |