ALSA: usb-audio: Add sanity checks to FE parser

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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 12 insertions, 0 deletions

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 1beb5b4d027e..b8ce651e392c 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1469,6 +1469,12 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid,
         __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,
@@ -1486,6 +1492,12 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid,
                 }
         } 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;