From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934396Ab3BMQNY (ORCPT ); Wed, 13 Feb 2013 11:13:24 -0500 Received: from www.linutronix.de ([62.245.132.108]:59743 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934383Ab3BMQNU (ORCPT ); Wed, 13 Feb 2013 11:13:20 -0500 From: Sebastian Andrzej Siewior To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, linux-rt-users@vger.kernel.org, Carsten Emde , Christoph Lameter , Pekka Enberg , Thomas Gleixner , Sebastian Andrzej Siewior Subject: [PATCH 09/16] FIX [1/2] slub: Do not dereference NULL pointer in node_match Date: Wed, 13 Feb 2013 17:12:04 +0100 Message-Id: <1360771932-27150-10-git-send-email-bigeasy@linutronix.de> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1360771932-27150-1-git-send-email-bigeasy@linutronix.de> References: <1360771932-27150-1-git-send-email-bigeasy@linutronix.de> X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Christoph Lameter 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. Signed-off-by: Christoph Lameter Cc: Steven Rostedt Cc: Pekka Enberg Signed-off-by: Thomas Gleixner [bigeasy@linutronix: replace page with c->page] Signed-off-by: Sebastian Andrzej Siewior --- mm/slub.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index 5710788..08eb4c1 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2038,7 +2038,7 @@ static void flush_all(struct kmem_cache *s) static inline int node_match(struct kmem_cache_cpu *c, int node) { #ifdef CONFIG_NUMA - if (node != NUMA_NO_NODE && c->node != node) + if (!c->page || (node != NUMA_NO_NODE && c->node != node)) return 0; #endif return 1; -- 1.7.10.4