From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752707AbZHJSn2 (ORCPT ); Mon, 10 Aug 2009 14:43:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752123AbZHJSn1 (ORCPT ); Mon, 10 Aug 2009 14:43:27 -0400 Received: from hera.kernel.org ([140.211.167.34]:36672 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751985AbZHJSn0 (ORCPT ); Mon, 10 Aug 2009 14:43:26 -0400 Date: Mon, 10 Aug 2009 18:42:34 GMT From: tip-bot for Darren Hart To: linux-tip-commits@vger.kernel.org Cc: linux-kernel@vger.kernel.org, dvhltc@us.ibm.com, hpa@zytor.com, mingo@redhat.com, johnstul@linux.vnet.ibm.com, eric.dumazet@gmail.com, jkacur@redhat.com, peterz@infradead.org, dino@in.ibm.com, rostedt@goodmis.org, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, dvhltc@us.ibm.com, linux-kernel@vger.kernel.org, jkacur@redhat.com, eric.dumazet@gmail.com, johnstul@linux.vnet.ibm.com, rostedt@goodmis.org, peterz@infradead.org, dino@in.ibm.com, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <4A7CA8C0.7010809@us.ibm.com> References: <4A7CA8C0.7010809@us.ibm.com> Subject: [tip:core/urgent] futex: Fix handling of bad requeue syscall pairing Message-ID: Git-Commit-ID: 392741e0a4e17c82e3978b7fcbf04291294dc0a1 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Mon, 10 Aug 2009 18:42:38 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 392741e0a4e17c82e3978b7fcbf04291294dc0a1 Gitweb: http://git.kernel.org/tip/392741e0a4e17c82e3978b7fcbf04291294dc0a1 Author: Darren Hart AuthorDate: Fri, 7 Aug 2009 15:20:48 -0700 Committer: Ingo Molnar CommitDate: Mon, 10 Aug 2009 20:38:11 +0200 futex: Fix handling of bad requeue syscall pairing If futex_requeue(requeue_pi=1) finds a futex_q that was created by a call other the futex_wait_requeue_pi(), the q.rt_waiter may be null. If so, this will result in an oops from the following call graph: futex_requeue() rt_mutex_start_proxy_lock() task_blocks_on_rt_mutex() waiter->task dereference OOPS We currently WARN_ON() if this is detected, clearly this is inadequate. If we detect a mispairing in futex_requeue(), bail out, seding -EINVAL to user-space. V2: Fix parenthesis warnings. Signed-off-by: Darren Hart Acked-by: Peter Zijlstra Cc: Steven Rostedt Cc: John Kacur Cc: Eric Dumazet Cc: Dinakar Guniguntala Cc: John Stultz LKML-Reference: <4A7CA8C0.7010809@us.ibm.com> Signed-off-by: Ingo Molnar --- kernel/futex.c | 11 +++++++++-- 1 files changed, 9 insertions(+), 2 deletions(-) diff --git a/kernel/futex.c b/kernel/futex.c index 8cc3ee1..e18cfbd 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1256,8 +1256,15 @@ retry_private: if (!match_futex(&this->key, &key1)) continue; - WARN_ON(!requeue_pi && this->rt_waiter); - WARN_ON(requeue_pi && !this->rt_waiter); + /* + * FUTEX_WAIT_REQEUE_PI and FUTEX_CMP_REQUEUE_PI should always + * be paired with each other and no other futex ops. + */ + if ((requeue_pi && !this->rt_waiter) || + (!requeue_pi && this->rt_waiter)) { + ret = -EINVAL; + break; + } /* * Wake nr_wake waiters. For requeue_pi, if we acquired the