slub: fix a possible memleak in __slab_alloc()
authorEric Dumazet <eric.dumazet@gmail.com>
Tue, 13 Dec 2011 03:57:06 +0000 (04:57 +0100)
committerGreg Kroah-Hartman <gregkh@suse.de>
Wed, 18 Jan 2012 15:31:57 +0000 (07:31 -0800)
commitea509eb0fb85a1c2704d932ae6095d3a2995a589
treebcc4eee2bbfc80492e4e241810bb656149090be8
parentd70357fd5682b8d868a86551125b2d3bbc0f2cf4
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 <zhihua.che@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
mm/slub.c