Commit 43d5ca88 authored by Takashi Iwai's avatar Takashi Iwai

ALSA: usb-audio: Fix potential out-of-bounds shift

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@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20201209084552.17109-1-tiwai@suse.deSigned-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent e5fab13a
...@@ -39,6 +39,8 @@ static u64 parse_audio_format_i_type(struct snd_usb_audio *chip, ...@@ -39,6 +39,8 @@ static u64 parse_audio_format_i_type(struct snd_usb_audio *chip,
case UAC_VERSION_1: case UAC_VERSION_1:
default: { default: {
struct uac_format_type_i_discrete_descriptor *fmt = _fmt; struct uac_format_type_i_discrete_descriptor *fmt = _fmt;
if (format >= 64)
return 0; /* invalid format */
sample_width = fmt->bBitResolution; sample_width = fmt->bBitResolution;
sample_bytes = fmt->bSubframeSize; sample_bytes = fmt->bSubframeSize;
format = 1ULL << format; format = 1ULL << format;
......
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