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ALSA: usb-audio: Fix potential out-of-bound access at parsing SU

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commit f658f17b5e0e339935dca23e77e0f3cad591926b upstream.

The usb-audio driver may trigger an out-of-bound access at parsing a
malformed selector unit, as it checks the header length only after
evaluating bNrInPins field, which can be already above the given
length.  Fix it by adding the length check beforehand.

Fixes: 99fc86450c43 ("ALSA: usb-mixer: parse descriptors with structs")
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Takashi Iwai 2017-11-21 17:00:32 +01:00 committed by Greg Kroah-Hartman
parent 85cc020b46
commit 23353220b5
1 changed files with 2 additions and 1 deletions
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3
sound/usb/mixer.c
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@ -2092,7 +2092,8 @@ static int parse_audio_selector_unit(struct mixer_build *state, int unitid,
const struct usbmix_name_map *map;
char **namelist;
if (!desc->bNrInPins || desc->bLength < 5 + desc->bNrInPins) {
if (desc->bLength < 5 || !desc->bNrInPins ||
desc->bLength < 5 + desc->bNrInPins) {
usb_audio_err(state->chip,
"invalid SELECTOR UNIT descriptor %d\n", unitid);
return -EINVAL;