Commit 2f38cf73 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: usb: Fix UBSAN warning in parse_audio_unit() 



A malformed USB descriptor may pass the lengthy mixer description with
a lot of channels, and this may overflow the 32bit integer shift
size, as caught by syzbot UBSAN test.  Although this won't cause any
real trouble, it's better to address.

This patch introduces a sanity check of the number of channels to bail
out the parsing when too many channels are found.

Reported-by: default avatar <syzbot+78d5b129a762182225aa@syzkaller.appspotmail.com>
Closes: https://lore.kernel.org/0000000000000adac5061d3c7355@google.com
Link: https://patch.msgid.link/20240715123619.26612-1-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 5fa87a08

sound/usb/mixer.c

+7 −0
Original line number Diff line number Diff line
@@ -2014,6 +2014,13 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid, 
		bmaControls = ftr->bmaControls;

	}



	if (channels > 32) {

		usb_audio_info(state->chip,

			       "usbmixer: too many channels (%d) in unit %d\n",

			       channels, unitid);

		return -EINVAL;

	}



	/* parse the source unit */

	err = parse_audio_unit(state, hdr->bSourceID);

	if (err < 0)