From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756584Ab2APSts (ORCPT ); Mon, 16 Jan 2012 13:49:48 -0500 Received: from cantor2.suse.de ([195.135.220.15]:43049 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755820Ab2APStp (ORCPT ); Mon, 16 Jan 2012 13:49:45 -0500 X-Mailbox-Line: From gregkh@clark.kroah.org Mon Jan 16 10:45:19 2012 Message-Id: <20120116184519.345383502@clark.kroah.org> User-Agent: quilt/0.50-25.1 Date: Mon, 16 Jan 2012 10:45:10 -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: [43/48] slub: fix a possible memleak in __slab_alloc() In-Reply-To: <20120116184527.GA11972@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.1-stable review patch. If anyone has any objections, please let me know. ------------------ 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 @@ -2077,6 +2077,11 @@ static void *__slab_alloc(struct kmem_ca 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 {