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| author | Andy Lutomirski | 2014-03-17 23:22:11 +0100 |
|---|---|---|
| committer | H. Peter Anvin | 2014-03-18 20:52:44 +0100 |
| commit | 309944be296efbb3ca4737d12ef49d2ba97cbecc (patch) | |
| tree | 56fefddab5690352d3c441835eacdf89390a76c0 | |
| parent | x86, vdso: Add 32 bit VDSO time support for 64 bit kernel (diff) | |
| download | kernel-qcow2-linux-309944be296efbb3ca4737d12ef49d2ba97cbecc.tar.gz kernel-qcow2-linux-309944be296efbb3ca4737d12ef49d2ba97cbecc.tar.xz kernel-qcow2-linux-309944be296efbb3ca4737d12ef49d2ba97cbecc.zip | |
x86, vdso: Zero-pad the VVAR page
By coincidence, the VVAR page is at the end of an ELF segment. As a
result, if it ends up being a partial page, the kernel loader will
leave garbage behind at the end of the vvar page. Zero-pad it to a
full page to fix this issue.
This has probably been broken since the VVAR page was introduced.
On QEMU, if you dump the run-time contents of the VVAR page, you can
find entertaining strings from seabios left behind.
It's remotely possible that this is a security bug -- conceivably
there's some BIOS out there that leaves something sensitive in the
few K of memory that is exposed to userspace.
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Link: http://lkml.kernel.org/r/1395094933-14252-12-git-send-email-stefani@seibold.net
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
| -rw-r--r-- | arch/x86/kernel/vmlinux.lds.S | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index 1d4897baf1cc..49edf2dd3613 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -164,6 +164,11 @@ SECTIONS #undef __VVAR_KERNEL_LDS #undef EMIT_VVAR + /* + * Pad the rest of the page with zeros. Otherwise the loader + * can leave garbage here. + */ + . = __vvar_beginning_hack + PAGE_SIZE; } :data . = ALIGN(__vvar_page + PAGE_SIZE, PAGE_SIZE); |