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authorEric Dumazet <eric.dumazet@gmail.com>2011-12-13 04:57:06 +0100
committerPekka Enberg <penberg@kernel.org>2011-12-13 22:11:21 +0200
commit73736e0387ba0e6d2b703407b4d26168d31516a7 (patch)
tree448f2d85f82462096d55c93f15cea9876665faaa /mm/slub.c
parent25f4379b8c79066c4be0e5995f37f5265733b801 (diff)
downloadlwn-73736e0387ba0e6d2b703407b4d26168d31516a7.tar.gz
lwn-73736e0387ba0e6d2b703407b4d26168d31516a7.zip
slub: fix a possible memleak in __slab_alloc()
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. Cc: <stable@vger.kernel.org> [2.6.39+] 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>
Diffstat (limited to 'mm/slub.c')
-rw-r--r--mm/slub.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/mm/slub.c b/mm/slub.c
index 108ed03fb422..5e410a95abaf 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -2169,6 +2169,11 @@ redo:
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 {