From: Christoph Lameter <cl@linux.com>
To: Simon Jeons <simon.jeons@gmail.com>
Cc: Pekka Enberg <penberg@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
RT <linux-rt-users@vger.kernel.org>,
Clark Williams <clark@redhat.com>, John Kacur <jkacur@gmail.com>,
"Luis Claudio R. Goncalves" <lgoncalv@redhat.com>,
Joonsoo Kim <js1304@gmail.com>,
Glauber Costa <glommer@parallels.com>,
linux-mm@kvack.org, David Rientjes <rientjes@google.com>,
elezegarcia@gmail.com
Subject: Re: FIX [1/2] slub: Do not dereference NULL pointer in node_match
Date: Thu, 24 Jan 2013 15:14:43 +0000 [thread overview]
Message-ID: <0000013c6d200e1d-03ae09c1-6fb8-42eb-ab6c-8fcae05fdb6e-000000@email.amazonses.com> (raw)
In-Reply-To: <1358988824.3351.5.camel@kernel>
On Wed, 23 Jan 2013, Simon Jeons wrote:
> On Wed, 2013-01-23 at 21:45 +0000, Christoph Lameter wrote:
> > The variables accessed in slab_alloc are volatile and therefore
> > the page pointer passed to node_match can be NULL. The processing
> > of data in slab_alloc is tentative until either the cmpxhchg
> > succeeds or the __slab_alloc slowpath is invoked. Both are
> > able to perform the same allocation from the freelist.
> >
> > Check for the NULL pointer in node_match.
> >
> > A false positive will lead to a retry of the loop in __slab_alloc.
>
> Hi Christoph,
>
> Since page_to_nid(NULL) will trigger bug, then how can run into
> __slab_alloc?
page = NULL
->
node_match(NULL, xx) = 0
->
call into __slab_alloc.
__slab_alloc() will check for !c->page which requires the assignment of a
new per cpu slab page.
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next prev parent reply other threads:[~2013-01-24 15:14 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20130123214514.370647954@linux.com>
2013-01-23 21:45 ` FIX [1/2] slub: Do not dereference NULL pointer in node_match Christoph Lameter
2013-01-23 21:45 ` Christoph Lameter
2013-01-24 0:53 ` Simon Jeons
2013-01-24 0:53 ` Simon Jeons
2013-01-24 15:14 ` Christoph Lameter [this message]
2013-01-25 8:11 ` Simon Jeons
2013-01-25 8:11 ` Simon Jeons
2013-01-25 14:53 ` Christoph Lameter
2013-02-01 10:23 ` Pekka Enberg
2013-02-01 10:23 ` Pekka Enberg
2013-02-01 11:51 ` Steven Rostedt
2013-02-01 11:51 ` Steven Rostedt
2013-01-23 21:45 ` FIX [2/2] slub: tid must be retrieved from the percpu area of the current processor Christoph Lameter
2013-01-23 21:45 ` Christoph Lameter
2013-02-01 10:24 ` Pekka Enberg
2013-02-01 10:24 ` Pekka Enberg
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