snd_usb_mixer_controls_badd() that parses UAC3 BADD profiles misses a NULL check for the given interfaces. When a malformed USB descriptor is passed, this may lead to an Oops, as spotted by syzkaller. Skip the iteration if the interface doesn't exist for avoiding the crash.

Fixes: 17156f23e93c ("ALSA: usb: add UAC3 BADD profiles support") Reported-by: syzbot+a36ab65c6653d7ccdd62@syzkaller.appspotmail.com Suggested-by: Dan Carpenter dan.carpenter@oracle.com Cc: stable@vger.kernel.org Signed-off-by: Takashi Iwai tiwai@suse.de --- sound/usb/mixer.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c index 45eee5cc312e..6cd4ff09c5ee 100644 --- a/sound/usb/mixer.c +++ b/sound/usb/mixer.c @@ -2930,6 +2930,9 @@ static int snd_usb_mixer_controls_badd(struct usb_mixer_interface *mixer, continue;

iface = usb_ifnum_to_if(dev, intf); + if (!iface) + continue; + num = iface->num_altsetting;

if (num < 2)