Patch "ALSA: pcm: Remove yet superfluous WARN_ON()" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

ALSA: pcm: Remove yet superfluous WARN_ON()

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
alsa-pcm-remove-yet-superfluous-warn_on.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Takashi Iwai <[email protected]>
Date: Wed, 10 Jan 2018 23:48:05 +0100
Subject: ALSA: pcm: Remove yet superfluous WARN_ON()

From: Takashi Iwai <[email protected]>

commit 23b19b7b50fe1867da8d431eea9cd3e4b6328c2c upstream.

muldiv32() contains a snd_BUG_ON() (which is morphed as WARN_ON() with debug option) for checking the case of 0 / 0. This would be helpful if this happens only as a logical error; however, since the hw refine is performed with any data set provided by user, the inconsistent values that can trigger such a condition might be passed easily. Actually, syzbot caught this by passing some zero'ed old hw_params ioctl.

So, having snd_BUG_ON() there is simply superfluous and rather harmful to give unnecessary confusions. Let's get rid of it.

---
 sound/core/pcm_lib.c |    1 -
 1 file changed, 1 deletion(-)

@@ -578,7 +578,6 @@ static inline unsigned int muldiv32(unsi
 {
 	u_int64_t n = (u_int64_t) a * b;
 	if (c == 0) {
-		snd_BUG_ON(!n);
 		*r = 0;
 		return UINT_MAX;
 	}

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/alsa-pcm-remove-yet-superfluous-warn_on.patch queue-4.9/alsa-hda-apply-the-existing-quirk-to-imac-14-1.patch queue-4.9/alsa-hda-apply-headphone-noise-quirk-for-another-dell-xps-13-variant.patch queue-4.9/alsa-seq-make-ioctls-race-free.patch