syzbot spotted a potential out-of-bounds shift in the USB-audio format
parser that receives the arbitrary shift value from the USB
descriptor.
Add a range check for avoiding the undefined behavior.
Reported-by: syzbot+df7dc146ebdd6435eea3@xxxxxxxxxxxxxxxxxxxxxxxxx
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
sound/usb/format.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/sound/usb/format.c b/sound/usb/format.c
index 93459ba228d3..9ebc5d202c87 100644
--- a/sound/usb/format.c
+++ b/sound/usb/format.c
@@ -39,6 +39,8 @@ static u64 parse_audio_format_i_type(struct snd_usb_audio *chip,
case UAC_VERSION_1:
default: {
struct uac_format_type_i_discrete_descriptor *fmt = _fmt;
+ if (format >= 64)
+ return 0; /* invalid format */
sample_width = fmt->bBitResolution;
sample_bytes = fmt->bSubframeSize;
format = 1ULL << format;
--
2.26.2
