[PATCH 4.4 33/96] ALSA: usb-audio: Add sanity checks to FE parser

Greg Kroah-Hartman
2017-11-28T10:28:51Z

From: Takashi Iwai <tiwai@suse.de>

commit d937cd6790a2bef2d07b500487646bd794c039bb upstream.

When the usb-audio descriptor contains the malformed feature unit
description with a too short length, the driver may access
out-of-bounds. Add a sanity check of the header size at the beginning
of parse_audio_feature_unit().

Fixes: 23caaf19b11e ("ALSA: usb-mixer: Add support for Audio Class v2.0")
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
sound/usb/mixer.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1397,6 +1397,12 @@ static int parse_audio_feature_unit(stru
__u8 *bmaControls;

if (state->mixer->protocol == UAC_VERSION_1) {
+ if (hdr->bLength < 7) {
+ usb_audio_err(state->chip,
+ "unit %u: invalid UAC_FEATURE_UNIT descriptor\n",
+ unitid);
+ return -EINVAL;
+ }
csize = hdr->bControlSize;
if (!csize) {
usb_audio_dbg(state->chip,
@@ -1414,6 +1420,12 @@ static int parse_audio_feature_unit(stru
}
} else {
struct uac2_feature_unit_descriptor *ftr = _ftr;
+ if (hdr->bLength < 6) {
+ usb_audio_err(state->chip,
+ "unit %u: invalid UAC_FEATURE_UNIT descriptor\n",
+ unitid);
+ return -EINVAL;
+ }
csize = 4;
channels = (hdr->bLength - 6) / 4 - 1;
bmaControls = ftr->bmaControls;