From cf8715aecc5bc0ae7ad0fcc0cd9887d3bf0f81a6 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Mon, 15 Jul 2024 14:35:54 +0200 Subject: [PATCH] ALSA: usb: Fix UBSAN warning in parse_audio_unit() [ Upstream commit 2f38cf730caedaeacdefb7ff35b0a3c1168117f9 ] 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: 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: Takashi Iwai Signed-off-by: Sasha Levin --- sound/usb/mixer.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c index 5699a62d1767..34ded71cb807 100644 --- a/sound/usb/mixer.c +++ b/sound/usb/mixer.c @@ -2023,6 +2023,13 @@ 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)