ALSA: hda - Fix possible zero-division

Check the TLV db scale result before actually dividing in vmaster
slave init code.  Also mask TLV_DB_SCALE_MUTE bit so that the right
value is obtained even if this bit is set by the codec driver.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 7 insertions, 2 deletions

diff --git a/sound/pci/hda/hda_codec.c b/sound/pci/hda/hda_codec.c
index de1a7670ba0d..33c01d551aa4 100644
--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -2676,8 +2676,13 @@ static int get_kctl_0dB_offset(struct snd_kcontrol *kctl)
                 set_fs(fs);
         } else if (kctl->vd[0].access & SNDRV_CTL_ELEM_ACCESS_TLV_READ)
                 tlv = kctl->tlv.p;
-        if (tlv && tlv[0] == SNDRV_CTL_TLVT_DB_SCALE)
-                val = -tlv[2] / tlv[3];
+        if (tlv && tlv[0] == SNDRV_CTL_TLVT_DB_SCALE) {
+                int step = tlv[3];
+                step &= ~TLV_DB_SCALE_MUTE;
+                if (!step)
+                        return -1;
+                val = -tlv[2] / step;
+        }
         return val;
 }