| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 083/120] x86/cpu: Fix bootup crashes by sanitizing the argument of the clearcpuid= command-line option | Date | Wed, 18 Jan 2017 11:46:41 +0100 |
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4.9-stable review patch. If anyone has any objections, please let me know.
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From: Lukasz Odzioba <lukasz.odzioba@intel.com>
commit dd853fd216d1485ed3045ff772079cc8689a9a4a upstream.
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/x86/kernel/cpu/common.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1275,7 +1275,7 @@ static __init int setup_disablecpuid(cha { 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;
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