From: Dave Jones <davej@redhat.com>
To: Linux Kernel <linux-kernel@vger.kernel.org>,
bhutchings@solarflare.com, linux-mm@kvack.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: mpol_to_str revisited.
Date: Mon, 8 Oct 2012 11:15:52 -0400 [thread overview]
Message-ID: <20121008151552.GA10881@redhat.com> (raw)
In-Reply-To: <20121008150949.GA15130@redhat.com>
On Mon, Oct 08, 2012 at 11:09:49AM -0400, Dave Jones wrote:
> Last month I sent in 80de7c3138ee9fd86a98696fd2cf7ad89b995d0a to remove
> a user triggerable BUG in mempolicy.
>
> Ben Hutchings pointed out to me that my change introduced a potential leak
> of stack contents to userspace, because none of the callers check the return value.
>
> This patch adds the missing return checking, and also clears the buffer beforehand.
>
> Reported-by: Ben Hutchings <bhutchings@solarflare.com>
> Cc: stable@kernel.org
> Signed-off-by: Dave Jones <davej@redhat.com>
>
> ---
> unanswered question: why are the buffer sizes here different ? which is correct?
A further unanswered question is how the state got so screwed up that we hit that
default case at all. Looking at the original report: https://lkml.org/lkml/2012/9/6/356
What's in RAX looks suspiciously like left-over slab poison.
If pol->mode was poisoned, that smells like we have a race where policy is getting freed
while another process is reading it.
Am I missing something, or is there no locking around that at all ?
Dave
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WARNING: multiple messages have this Message-ID (diff)
From: Dave Jones <davej@redhat.com>
To: Linux Kernel <linux-kernel@vger.kernel.org>,
bhutchings@solarflare.com, linux-mm@kvack.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: mpol_to_str revisited.
Date: Mon, 8 Oct 2012 11:15:52 -0400 [thread overview]
Message-ID: <20121008151552.GA10881@redhat.com> (raw)
In-Reply-To: <20121008150949.GA15130@redhat.com>
On Mon, Oct 08, 2012 at 11:09:49AM -0400, Dave Jones wrote:
> Last month I sent in 80de7c3138ee9fd86a98696fd2cf7ad89b995d0a to remove
> a user triggerable BUG in mempolicy.
>
> Ben Hutchings pointed out to me that my change introduced a potential leak
> of stack contents to userspace, because none of the callers check the return value.
>
> This patch adds the missing return checking, and also clears the buffer beforehand.
>
> Reported-by: Ben Hutchings <bhutchings@solarflare.com>
> Cc: stable@kernel.org
> Signed-off-by: Dave Jones <davej@redhat.com>
>
> ---
> unanswered question: why are the buffer sizes here different ? which is correct?
A further unanswered question is how the state got so screwed up that we hit that
default case at all. Looking at the original report: https://lkml.org/lkml/2012/9/6/356
What's in RAX looks suspiciously like left-over slab poison.
If pol->mode was poisoned, that smells like we have a race where policy is getting freed
while another process is reading it.
Am I missing something, or is there no locking around that at all ?
Dave
next prev parent reply other threads:[~2012-10-08 15:15 UTC|newest]
Thread overview: 117+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-08 15:09 mpol_to_str revisited Dave Jones
2012-10-08 15:09 ` Dave Jones
2012-10-08 15:15 ` Dave Jones [this message]
2012-10-08 15:15 ` Dave Jones
2012-10-08 20:46 ` David Rientjes
2012-10-08 20:46 ` David Rientjes
2012-10-08 20:35 ` David Rientjes
2012-10-08 20:35 ` David Rientjes
2012-10-08 20:52 ` Dave Jones
2012-10-08 20:52 ` Dave Jones
2012-10-16 0:48 ` David Rientjes
2012-10-16 0:48 ` David Rientjes
2012-10-09 0:33 ` Ben Hutchings
2012-10-16 2:34 ` KOSAKI Motohiro
2012-10-16 2:34 ` KOSAKI Motohiro
2012-10-16 3:58 ` David Rientjes
2012-10-16 3:58 ` David Rientjes
2012-10-16 5:10 ` KOSAKI Motohiro
2012-10-16 5:10 ` KOSAKI Motohiro
2012-10-16 6:10 ` David Rientjes
2012-10-16 6:10 ` David Rientjes
2012-10-16 23:39 ` KOSAKI Motohiro
2012-10-16 23:39 ` KOSAKI Motohiro
2012-10-17 0:12 ` David Rientjes
2012-10-17 0:12 ` David Rientjes
2012-10-17 0:31 ` [patch for-3.7] mm, mempolicy: fix printing stack contents in numa_maps David Rientjes
2012-10-17 0:31 ` David Rientjes
2012-10-17 1:38 ` KOSAKI Motohiro
2012-10-17 1:38 ` KOSAKI Motohiro
2012-10-17 1:49 ` David Rientjes
2012-10-17 1:49 ` David Rientjes
2012-10-17 1:53 ` KOSAKI Motohiro
2012-10-17 1:53 ` KOSAKI Motohiro
2012-10-17 4:05 ` Dave Jones
2012-10-17 4:05 ` Dave Jones
2012-10-17 5:24 ` David Rientjes
2012-10-17 5:24 ` David Rientjes
2012-10-17 5:42 ` Kamezawa Hiroyuki
2012-10-17 5:42 ` Kamezawa Hiroyuki
2012-10-17 8:49 ` KOSAKI Motohiro
2012-10-17 8:49 ` KOSAKI Motohiro
2012-10-17 19:50 ` David Rientjes
2012-10-17 19:50 ` David Rientjes
2012-10-17 21:05 ` KOSAKI Motohiro
2012-10-17 21:05 ` KOSAKI Motohiro
2012-10-17 21:27 ` David Rientjes
2012-10-17 21:27 ` David Rientjes
2012-10-17 18:14 ` Dave Jones
2012-10-17 18:14 ` Dave Jones
2012-10-17 19:21 ` David Rientjes
2012-10-17 19:21 ` David Rientjes
2012-10-17 19:32 ` Dave Jones
2012-10-17 19:32 ` Dave Jones
2012-10-17 19:38 ` David Rientjes
2012-10-17 19:38 ` David Rientjes
2012-10-17 19:45 ` Dave Jones
2012-10-17 19:45 ` Dave Jones
2012-10-17 20:28 ` [patch for-3.7] mm, mempolicy: avoid taking mutex inside spinlock when reading numa_maps David Rientjes
2012-10-17 20:28 ` David Rientjes
2012-10-17 21:31 ` [patch for-3.7 v2] " David Rientjes
2012-10-17 21:31 ` David Rientjes
2012-10-18 4:06 ` Kamezawa Hiroyuki
2012-10-18 4:06 ` Kamezawa Hiroyuki
2012-10-18 4:14 ` Linus Torvalds
2012-10-18 4:14 ` Linus Torvalds
2012-10-18 4:41 ` Kamezawa Hiroyuki
2012-10-18 4:41 ` Kamezawa Hiroyuki
2012-10-18 4:34 ` Kamezawa Hiroyuki
2012-10-18 4:34 ` Kamezawa Hiroyuki
2012-10-18 20:03 ` David Rientjes
2012-10-18 20:03 ` David Rientjes
2012-10-19 8:35 ` [patch for-3.7 v3] mm, mempolicy: hold task->mempolicy refcount while " Kamezawa Hiroyuki
2012-10-19 8:35 ` Kamezawa Hiroyuki
2012-10-19 9:28 ` David Rientjes
2012-10-19 9:28 ` David Rientjes
2012-10-22 2:47 ` Kamezawa Hiroyuki
2012-10-22 2:47 ` Kamezawa Hiroyuki
2012-10-22 20:55 ` Andrew Morton
2012-10-22 20:55 ` Andrew Morton
2012-10-22 20:56 ` David Rientjes
2012-10-22 20:56 ` David Rientjes
2012-10-19 19:15 ` KOSAKI Motohiro
2012-10-19 19:15 ` KOSAKI Motohiro
2012-10-19 6:51 ` [patch for-3.7 v2] mm, mempolicy: avoid taking mutex inside spinlock when " KOSAKI Motohiro
2012-10-19 6:51 ` KOSAKI Motohiro
2012-10-18 4:35 ` David Rientjes
2012-10-18 4:35 ` David Rientjes
2012-10-24 23:30 ` [patch for-3.7] mm, mempolicy: fix printing stack contents in numa_maps Sasha Levin
2012-10-24 23:30 ` Sasha Levin
2012-10-24 23:34 ` David Rientjes
2012-10-24 23:34 ` David Rientjes
2012-10-24 23:37 ` Sasha Levin
2012-10-24 23:37 ` Sasha Levin
2012-10-25 0:08 ` David Rientjes
2012-10-25 0:08 ` David Rientjes
2012-10-25 0:54 ` KOSAKI Motohiro
2012-10-25 0:54 ` KOSAKI Motohiro
2012-10-25 1:15 ` David Rientjes
2012-10-25 1:15 ` David Rientjes
2012-10-25 12:19 ` Peter Zijlstra
2012-10-25 12:19 ` Peter Zijlstra
2012-10-25 14:39 ` Peter Zijlstra
2012-10-25 14:39 ` Peter Zijlstra
2012-10-25 17:23 ` Sasha Levin
2012-10-25 17:23 ` Sasha Levin
2012-10-25 20:22 ` David Rientjes
2012-10-25 20:22 ` David Rientjes
2012-10-25 23:09 ` Linus Torvalds
2012-10-25 23:09 ` Linus Torvalds
2012-10-26 8:48 ` Peter Zijlstra
2012-10-26 8:48 ` Peter Zijlstra
2012-10-31 18:29 ` Sasha Levin
2012-10-31 18:29 ` Sasha Levin
2012-11-21 0:59 ` Sasha Levin
2012-11-21 0:59 ` Sasha Levin
2012-10-17 1:33 ` mpol_to_str revisited KOSAKI Motohiro
2012-10-17 1:33 ` KOSAKI Motohiro
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