Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755557AbdLOKpj (ORCPT ); Fri, 15 Dec 2017 05:45:39 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:33728 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755206AbdLOJqU (ORCPT ); Fri, 15 Dec 2017 04:46:20 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot , Takashi Iwai Subject: [PATCH 4.4 019/105] ALSA: seq: Remove spurious WARN_ON() at timer check Date: Fri, 15 Dec 2017 10:44:17 +0100 Message-Id: <20171215092306.898955680@linuxfoundation.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171215092305.994559179@linuxfoundation.org> References: <20171215092305.994559179@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 999 Lines: 35 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Takashi Iwai commit 43a3542870328601be02fcc9d27b09db467336ef upstream. The use of snd_BUG_ON() in ALSA sequencer timer may lead to a spurious WARN_ON() when a slave timer is deployed as its backend and a corresponding master timer stops meanwhile. The symptom was triggered by syzkaller spontaneously. Since the NULL timer is valid there, rip off snd_BUG_ON(). Reported-by: syzbot Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/core/seq/seq_timer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/sound/core/seq/seq_timer.c +++ b/sound/core/seq/seq_timer.c @@ -355,7 +355,7 @@ static int initialize_timer(struct snd_s unsigned long freq; t = tmr->timeri->timer; - if (snd_BUG_ON(!t)) + if (!t) return -EINVAL; freq = tmr->preferred_resolution;