ALSA: usb-audio: Fix potential zero-division at parsing FU

parse_audio_feature_unit() contains a code dividing potentially with
zero when a malformed FU descriptor is passed.  Although there is
already a sanity check, it checks only the value zero, hence it can
still lead to a zero-division when a value 1 is passed there.

Fix it by correcting the sanity check (and the error message
thereof).

Fixes: 23caaf19b11e ("ALSA: usb-mixer: Add support for Audio Class v2.0")
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 61b348383de88fa282028a78603567fa513589b7..0537c632299082eb1c40617491a77c964fb9c011 100644 (file)
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1476,9 +1476,9 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid,
                        return -EINVAL;
                }
                csize = hdr->bControlSize;
-               if (!csize) {
+               if (csize <= 1) {
                        usb_audio_dbg(state->chip,
-                                     "unit %u: invalid bControlSize == 0\n",
+                                     "unit %u: invalid bControlSize <= 1\n",
                                      unitid);
                        return -EINVAL;
                }