From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-Id: <20120124023927.660375010@clark.kroah.org> Date: Mon, 23 Jan 2012 18:34:22 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Eric Dumazet , Christoph Lameter , Pekka Enberg Subject: [042/129] slub: fix a possible memleak in __slab_alloc() In-Reply-To: <20120124024041.GA18422@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ Content-Length: 1140 Lines: 41 From: Eric Dumazet 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 Signed-off-by: Eric Dumazet Acked-by: Christoph Lameter Signed-off-by: Pekka Enberg Signed-off-by: Greg Kroah-Hartman --- 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 {