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| author | Eric Dumazet <eric.dumazet@gmail.com> | 2011-12-13 04:57:06 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2012-01-18 07:31:57 -0800 |
| commit | ea509eb0fb85a1c2704d932ae6095d3a2995a589 (patch) | |
| tree | bcc4eee2bbfc80492e4e241810bb656149090be8 | |
| parent | d70357fd5682b8d868a86551125b2d3bbc0f2cf4 (diff) | |
| download | lwn-ea509eb0fb85a1c2704d932ae6095d3a2995a589.tar.gz lwn-ea509eb0fb85a1c2704d932ae6095d3a2995a589.zip | |
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>
| -rw-r--r-- | mm/slub.c | 5 |
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; + stat(s, ALLOC_SLOWPATH); do { |