This is a note to let you know that I've just added the patch titled
x86/cpu: Fix bootup crashes by sanitizing the argument of the 'clearcpuid=' command-line option
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-cpu-fix-bootup-crashes-by-sanitizing-the-argument-of-the-clearcpuid-command-line-option.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From dd853fd216d1485ed3045ff772079cc8689a9a4a Mon Sep 17 00:00:00 2001
From: Lukasz Odzioba <lukasz.odzioba@xxxxxxxxx>
Date: Wed, 28 Dec 2016 14:55:40 +0100
Subject: x86/cpu: Fix bootup crashes by sanitizing the argument of the 'clearcpuid=' command-line option
From: Lukasz Odzioba <lukasz.odzioba@xxxxxxxxx>
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@xxxxxxxxx>
Acked-by: Borislav Petkov <bp@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: andi.kleen@xxxxxxxxx
Cc: bp@xxxxxxxxx
Cc: dave.hansen@xxxxxxxxxxxxxxx
Cc: luto@xxxxxxxxxx
Cc: slaoub@xxxxxxxxx
Fixes: ac72e7888a61 ("x86: add generic clearcpuid=... option")
Link: http://lkml.kernel.org/r/1482933340-11857-1-git-send-email-lukasz.odzioba@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
@@ -1129,7 +1129,7 @@ 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;
Patches currently in stable-queue which might be from lukasz.odzioba@xxxxxxxxx are
queue-4.4/x86-cpu-fix-bootup-crashes-by-sanitizing-the-argument-of-the-clearcpuid-command-line-option.patch
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