From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753167AbeDIPSL (ORCPT ); Mon, 9 Apr 2018 11:18:11 -0400 Received: from mx2.suse.de ([195.135.220.15]:53924 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752677AbeDIPSI (ORCPT ); Mon, 9 Apr 2018 11:18:08 -0400 Date: Mon, 09 Apr 2018 17:18:05 +0200 Message-ID: From: Takashi Iwai To: syzbot Cc: , , , , Subject: Re: WARNING in snd_pcm_hw_params In-Reply-To: <001a113fe6c005d8ac056922c4c3@google.com> References: <001a113fe6c005d8ac056922c4c3@google.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/25.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 06 Apr 2018 02:02:02 +0200, syzbot wrote: > > WARNING: CPU: 0 PID: 4468 at sound/core/pcm_native.c:620 > snd_pcm_hw_params_choose sound/core/pcm_native.c:620 [inline] This is a WARN_ON() to catch the inconsistent hw_params call. This shouldn't happen in theory, but the reality looks weirder. The necessary "fix" is just to get rid of snd_BUG_ON(), but still wonder which condition it hits. If it's an empty parameter, the previous snd_pcm_hw_refine() should have caught and returned the error beforehand... In anyway this can't be a real crash, let's remove the warning to stop the chorus of syzbot birds. thanks, Takashi -- 8< -- From: Takashi Iwai Subject: [PATCH] ALSA: pcm: Remove WARN_ON() at snd_pcm_hw_params() error snd_pcm_hw_params() may hit WARN_ON() when an inconsistent parameter set is passed. Although this should have been caught by the former snd_pcm_hw_refine() and returned the error, syzkaller succeeded to pass through and hit the WARN_ON(), which in turn made it panic unnecessarily. For reducing this kind of noise, let's drop snd_BUG_ON() check. Reported-by: syzbot+803e0047ac3a3096bb4f@syzkaller.appspotmail.com Signed-off-by: Takashi Iwai --- sound/core/pcm_native.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index b84554893fab..35ffccea94c3 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -617,7 +617,7 @@ static int snd_pcm_hw_params_choose(struct snd_pcm_substream *pcm, changed = snd_pcm_hw_param_first(pcm, params, *v, NULL); else changed = snd_pcm_hw_param_last(pcm, params, *v, NULL); - if (snd_BUG_ON(changed < 0)) + if (changed < 0) return changed; if (changed == 0) continue; -- 2.16.3