Commit 43d5ca88 authored Dec 09, 2020 by 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.de


Signed-off-by: Takashi Iwai <tiwai@suse.de>

parent e5fab13a

sound/usb/format.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -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;

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