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 tiwai@suse.de 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 tiwai@suse.de --- 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;