From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "=?UTF-8?q?Dave=20 \"Trinity\" =20Jones?=" , Thomas Gleixner , Darren Hart , Davidlohr Bueso , Peter Zijlstra Subject: [PATCH 3.16 245/357] futex: Unlock hb->lock in futex_wait_requeue_pi() error path Date: Fri, 3 Oct 2014 14:30:31 -0700 Message-Id: <20141003212940.862527986@linuxfoundation.org> In-Reply-To: <20141003212933.458851516@linuxfoundation.org> References: <20141003212933.458851516@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Thomas Gleixner commit 13c42c2f43b19aab3195f2d357db00d1e885eaa8 upstream. futex_wait_requeue_pi() calls futex_wait_setup(). If futex_wait_setup() succeeds it returns with hb->lock held and preemption disabled. Now the sanity check after this does: if (match_futex(&q.key, &key2)) { ret = -EINVAL; goto out_put_keys; } which releases the keys but does not release hb->lock. So we happily return to user space with hb->lock held and therefor preemption disabled. Unlock hb->lock before taking the exit route. Reported-by: Dave "Trinity" Jones Signed-off-by: Thomas Gleixner Reviewed-by: Darren Hart Reviewed-by: Davidlohr Bueso Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1409112318500.4178@nanos Signed-off-by: Thomas Gleixner Signed-off-by: Greg Kroah-Hartman --- kernel/futex.c | 1 + 1 file changed, 1 insertion(+) --- a/kernel/futex.c +++ b/kernel/futex.c @@ -2628,6 +2628,7 @@ static int futex_wait_requeue_pi(u32 __u * shared futexes. We need to compare the keys: */ if (match_futex(&q.key, &key2)) { + queue_unlock(hb); ret = -EINVAL; goto out_put_keys; }