| | Date | Mon, 23 Jan 2012 18:34:22 -0800 | | From | Greg KH <> | | Subject | [042/129] slub: fix a possible memleak in __slab_alloc() |
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3.2-stable review patch. If anyone has any objections, please let me know.
------------------ Content-Length: 1140 Lines: 41 From: Eric Dumazet <eric.dumazet@gmail.com>
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 | 5 +++++ 1 file changed, 5 insertions(+) --- a/mm/slub.c +++ b/mm/slub.c @@ -2166,6 +2166,11 @@ 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 {
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