From ea509eb0fb85a1c2704d932ae6095d3a2995a589 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 13 Dec 2011 04:57:06 +0100 Subject: 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 --- mm/slub.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'mm/slub.c') 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; + stat(s, ALLOC_SLOWPATH); do { -- cgit v1.2.3