ALSA: pcm: Remove WARN_ON() at snd_pcm_hw_params() error

snd_pcm_hw_params() (more exactly snd_pcm_hw_params_choose()) contains
a check of the return error from snd_pcm_hw_param_first() and _last()
with snd_BUG_ON() -- i.e. it may trigger WARN_ON() depending on the
kconfig.

This was a valid check in the past, as these functions shouldn't
return any error if the parameters have been already refined via
snd_pcm_hw_refine() beforehand.  However, the recent rewrite
introduced a kmalloc() in snd_pcm_hw_refine() for removing VLA, and
this brought a possibility to trigger an error.  As a result, syzbot
caught lots of superfluous kernel WARN_ON() and paniced via fault
injection.

As the WARN_ON() is no longer valid with the introduction of
kmalloc(), let's drop snd_BUG_ON() check, in order to make the world
peaceful place again.

Reported-by: syzbot+803e0047ac3a3096bb4f@syzkaller.appspotmail.com
Fixes: 5730f9f7 ("ALSA: pcm: Remove VLA usage")
Signed-off-by: Takashi Iwai <tiwai@suse.de>

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;