Patch "ALSA: usb-audio: Fix potential zero-division at parsing FU" has been added to the 3.18-stable tree

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

ALSA: usb-audio: Fix potential zero-division at parsing FU

to the 3.18-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-usb-audio-fix-potential-zero-division-at-parsing-fu.patch
and it can be found in the queue-3.18 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: Tue, 21 Nov 2017 17:07:43 +0100
Subject: ALSA: usb-audio: Fix potential zero-division at parsing FU

From: Takashi Iwai <[email protected]>

commit 8428a8ebde2db1e988e41a58497a28beb7ce1705 upstream.

parse_audio_feature_unit() contains a code dividing potentially with zero when a malformed FU descriptor is passed. Although there is already a sanity check, it checks only the value zero, hence it can still lead to a zero-division when a value 1 is passed there.

Fix it by correcting the sanity check (and the error message thereof).

---
 sound/usb/mixer.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

@@ -1380,9 +1380,9 @@ static int parse_audio_feature_unit(stru
 			return -EINVAL;
 		}
 		csize = hdr->bControlSize;
-		if (!csize) {
+		if (csize <= 1) {
 			usb_audio_dbg(state->chip,
-				      "unit %u: invalid bControlSize == 0\n",
+				      "unit %u: invalid bControlSize <= 1\n",
 				      unitid);
 			return -EINVAL;
 		}

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

queue-3.18/alsa-usb-audio-fix-potential-zero-division-at-parsing-fu.patch queue-3.18/alsa-timer-remove-kernel-warning-at-compat-ioctl-error-paths.patch queue-3.18/alsa-hda-add-raven-pci-id.patch queue-3.18/alsa-usb-audio-add-sanity-checks-in-v2-clock-parsers.patch queue-3.18/alsa-usb-audio-fix-potential-out-of-bound-access-at-parsing-su.patch queue-3.18/alsa-usb-audio-add-sanity-checks-to-fe-parser.patch

Please drop this commit. This turned out to be buggy and bogus. It'll be reverted soon later.

thanks,

Takashi

Ok, will go drop it now from all of the stable trees, thanks for letting me know.

greg k-h