This is a note to let you know that I've just added the patch titled
slub: fix a possible memleak in __slab_alloc()
to the 3.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
slub-fix-a-possible-memleak-in-__slab_alloc.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 73736e0387ba0e6d2b703407b4d26168d31516a7 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <[email protected]>
Date: Tue, 13 Dec 2011 04:57:06 +0100
Subject: slub: fix a possible memleak in __slab_alloc()
From: Eric Dumazet <[email protected]>
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 <[email protected]>
Signed-off-by: Eric Dumazet <[email protected]>
Acked-by: Christoph Lameter <[email protected]>
Signed-off-by: Pekka Enberg <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
mm/slub.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1818,6 +1818,11 @@ static void *__slab_alloc(struct kmem_ca
if (unlikely(!node_match(c, node)))
goto another_slab;
+ /* must check again c->freelist in case of cpu migration or IRQ */
+ object = c->freelist;
+ if (object)
+ goto update_freelist;
+
stat(s, ALLOC_REFILL);
load_freelist:
@@ -1827,6 +1832,7 @@ load_freelist:
if (kmem_cache_debug(s))
goto debug;
+update_freelist:
c->freelist = get_freepointer(s, object);
page->inuse = page->objects;
page->freelist = NULL;
Patches currently in stable-queue which might be from [email protected] are
queue-3.0/perf-tools-fix-perf-stack-to-non-executable-on-x86_64.patch
queue-3.0/slub-fix-a-possible-memleak-in-__slab_alloc.patch
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