From: Lukasz Odzioba <lukasz.odzioba@intel.com>
Date: Wed, 28 Dec 2016 13:55:40 +0000 (+0100)
Subject: x86/cpu: Fix bootup crashes by sanitizing the argument of the 'clearcpuid=' command... 
X-Git-Tag: v3.2.87~117
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=237dfb6d038ee9281e07fe734f0e4671bf26492b;p=pandora-kernel.git

x86/cpu: Fix bootup crashes by sanitizing the argument of the 'clearcpuid=' command-line option

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: Ben Hutchings <ben@decadent.org.uk>
---

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