From 4d7868e6475d478172581828021bd8a356726679 Mon Sep 17 00:00:00 2001 From: Christoph Lameter Date: Wed, 23 Jan 2013 21:45:47 +0000 Subject: [PATCH] slub: Do not dereference NULL pointer in node_match 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 Signed-off-by: Pekka Enberg --- mm/slub.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index 21b3f004f614..8b1b99d399cb 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2042,7 +2042,7 @@ static void flush_all(struct kmem_cache *s) 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;