path: root/mm/slub.c
diff options
authorEric Dumazet <>2011-12-13 04:57:06 +0100
committerGreg Kroah-Hartman <>2012-01-18 07:31:57 -0800
commitea509eb0fb85a1c2704d932ae6095d3a2995a589 (patch)
treebcc4eee2bbfc80492e4e241810bb656149090be8 /mm/slub.c
parentd70357fd5682b8d868a86551125b2d3bbc0f2cf4 (diff)
slub: fix a possible memleak in __slab_alloc()
commit 73736e0387ba0e6d2b703407b4d26168d31516a7 upstream. Zhihua Che reported a possible memleak in slub allocator on CONFIG_PREEMPT=y builds. It is possible current thread migrates right before disabling irqs in __slab_alloc(). We must check again c->freelist, and perform a normal allocation instead of scratching c->freelist. Many thanks to Zhihua Che for spotting this bug, introduced in 2.6.39 V2: Its also possible an IRQ freed one (or several) object(s) and populated c->freelist, so its not a CONFIG_PREEMPT only problem. Reported-by: Zhihua Che <> Signed-off-by: Eric Dumazet <> Acked-by: Christoph Lameter <> Signed-off-by: Pekka Enberg <> Signed-off-by: Greg Kroah-Hartman <>
Diffstat (limited to 'mm/slub.c')
1 files changed, 5 insertions, 0 deletions
diff --git a/mm/slub.c b/mm/slub.c
index 7c54fe83a90c..f73234db904d 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2077,6 +2077,11 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
goto new_slab;
+ /* must check again c->freelist in case of cpu migration or IRQ */
+ object = c->freelist;
+ if (object)
+ goto load_freelist;
do {