ALSA: usb-audio: Avoid access before bLength check in build_audio_procunit()
commit f4351a199cc120ff9d59e06d02e8657d08e6cc46 upstream.
The parser for the processing unit reads bNrInPins field before the
bLength sanity check, which may lead to an out-of-bound access when a
malformed descriptor is given. Fix it by assignment after the bLength
check.
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index db8404e..64b90b8 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1882,7 +1882,7 @@
char *name)
{
struct uac_processing_unit_descriptor *desc = raw_desc;
- int num_ins = desc->bNrInPins;
+ int num_ins;
struct usb_mixer_elem_info *cval;
struct snd_kcontrol *kctl;
int i, err, nameid, type, len;
@@ -1897,7 +1897,13 @@
0, NULL, default_value_info
};
- if (desc->bLength < 13 || desc->bLength < 13 + num_ins ||
+ if (desc->bLength < 13) {
+ usb_audio_err(state->chip, "invalid %s descriptor (id %d)\n", name, unitid);
+ return -EINVAL;
+ }
+
+ num_ins = desc->bNrInPins;
+ if (desc->bLength < 13 + num_ins ||
desc->bLength < num_ins + uac_processing_unit_bControlSize(desc, state->mixer->protocol)) {
usb_audio_err(state->chip, "invalid %s descriptor (id %d)\n", name, unitid);
return -EINVAL;