From: Simon Jeons <simon.jeons@gmail.com>
To: Christoph Lameter <cl@linux.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: Wed, 23 Jan 2013 18:53:44 -0600 [thread overview]
Message-ID: <1358988824.3351.5.camel@kernel> (raw)
In-Reply-To: <0000013c695fbd30-9023bc55-f780-4d44-965f-ab4507e483d5-000000@email.amazonses.com>
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?
>
> Signed-off-by: Christoph Lameter <cl@linux.com>
>
> Index: linux/mm/slub.c
> ===================================================================
> --- linux.orig/mm/slub.c 2013-01-18 08:47:29.198954250 -0600
> +++ linux/mm/slub.c 2013-01-18 08:47:40.579126371 -0600
> @@ -2041,7 +2041,7 @@ static void flush_all(struct kmem_cache
> static inline int node_match(struct page *page, int node)
> {
> #ifdef CONFIG_NUMA
> - if (node != NUMA_NO_NODE && page_to_nid(page) != node)
> + if (!page || (node != NUMA_NO_NODE && page_to_nid(page) != node))
> return 0;
> #endif
> return 1;
>
> --
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next prev parent reply other threads:[~2013-01-24 0:53 UTC|newest]
Thread overview: 9+ 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
2013-01-24 0:53 ` Simon Jeons [this message]
2013-01-24 15:14 ` Christoph Lameter
2013-01-25 8:11 ` Simon Jeons
2013-01-25 14:53 ` Christoph Lameter
2013-02-01 10:23 ` Pekka Enberg
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
2013-02-01 10:24 ` Pekka Enberg
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