From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:35876 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934025AbdERNSn (ORCPT ); Thu, 18 May 2017 09:18:43 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dmitry Vyukov , Takashi Iwai , Amit Pundir Subject: [PATCH 3.18 45/49] ALSA: seq: Fix race at timer setup and close Date: Thu, 18 May 2017 15:16:54 +0200 Message-Id: <20170518131644.942826661@linuxfoundation.org> In-Reply-To: <20170518131643.028057293@linuxfoundation.org> References: <20170518131643.028057293@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Takashi Iwai commit 3567eb6af614dac436c4b16a8d426f9faed639b3 upstream. ALSA sequencer code has an open race between the timer setup ioctl and the close of the client. This was triggered by syzkaller fuzzer, and a use-after-free was caught there as a result. This patch papers over it by adding a proper queue->timer_mutex lock around the timer-related calls in the relevant code path. Reported-by: Dmitry Vyukov Tested-by: Dmitry Vyukov Signed-off-by: Takashi Iwai Signed-off-by: Amit Pundir Signed-off-by: Greg Kroah-Hartman --- sound/core/seq/seq_queue.c | 2 ++ 1 file changed, 2 insertions(+) --- a/sound/core/seq/seq_queue.c +++ b/sound/core/seq/seq_queue.c @@ -142,8 +142,10 @@ static struct snd_seq_queue *queue_new(i static void queue_delete(struct snd_seq_queue *q) { /* stop and release the timer */ + mutex_lock(&q->timer_mutex); snd_seq_timer_stop(q->timer); snd_seq_timer_close(q); + mutex_unlock(&q->timer_mutex); /* wait until access free */ snd_use_lock_sync(&q->use_lock); /* release resources... */