From: Takashi Iwai <tiwai@xxxxxxx>
commit 9435f2bb66874a0c4dd25e7c978957a7ca2c93b1 upstream.
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@xxxxxxxxxxxxxxxxxxxxxxxxx
Suggested-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20191122112840.24797-1-tiwai@xxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
sound/usb/mixer.c | 3 +++
1 file changed, 3 insertions(+)
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -2930,6 +2930,9 @@ static int snd_usb_mixer_controls_badd(s
continue;
iface = usb_ifnum_to_if(dev, intf);
+ if (!iface)
+ continue;
+
num = iface->num_altsetting;
if (num < 2)
