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authorLukasz Odzioba <lukasz.odzioba@intel.com>2016-12-28 14:55:40 +0100
committerIngo Molnar <mingo@kernel.org>2017-01-05 08:54:34 +0100
commitdd853fd216d1485ed3045ff772079cc8689a9a4a (patch)
tree4b351982ec908b819b9f3dff707fc99f1830d910
parentMerge tag 'xfs-for-linus-4.10-rc3' of git://git.kernel.org/pub/scm/fs/xfs/xfs... (diff)
downloadlinux-dd853fd216d1485ed3045ff772079cc8689a9a4a.tar.xz
linux-dd853fd216d1485ed3045ff772079cc8689a9a4a.zip
x86/cpu: Fix bootup crashes by sanitizing the argument of the 'clearcpuid=' command-line option
A negative number can be specified in the cmdline which will be used as setup_clear_cpu_cap() argument. With that we can clear/set some bit in memory predceeding boot_cpu_data/cpu_caps_cleared which may cause kernel to misbehave. This patch adds lower bound check to setup_disablecpuid(). Boris Petkov reproduced a crash: [ 1.234575] BUG: unable to handle kernel paging request at ffffffff858bd540 [ 1.236535] IP: memcpy_erms+0x6/0x10 Signed-off-by: Lukasz Odzioba <lukasz.odzioba@intel.com> Acked-by: Borislav Petkov <bp@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: andi.kleen@intel.com Cc: bp@alien8.de Cc: dave.hansen@linux.intel.com Cc: luto@kernel.org Cc: slaoub@gmail.com Fixes: ac72e7888a61 ("x86: add generic clearcpuid=... option") Link: http://lkml.kernel.org/r/1482933340-11857-1-git-send-email-lukasz.odzioba@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--arch/x86/kernel/cpu/common.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index dc1697ca5191..9bab7a8a4293 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1221,7 +1221,7 @@ static __init int setup_disablecpuid(char *arg)
{
int bit;
- if (get_option(&arg, &bit) && bit < NCAPINTS*32)
+ if (get_option(&arg, &bit) && bit >= 0 && bit < NCAPINTS * 32)
setup_clear_cpu_cap(bit);
else
return 0;