asoc: add null check for pcm pointer of snd_pcm_volume

In platform driver volume controls, add null check for
pcm pointer of struct snd_pcm_volume.

Change-Id: I511a79422eaeced6240849cbb665a289afdc5984
Signed-off-by: Xiaojun Sang <[email protected]>

asoc/msm-pcm-q6-noirq.c

@@ -732,6 +732,12 @@ static int msm_pcm_volume_ctl_get(struct snd_kcontrol *kcontrol,
 		pr_err("%s: vol is NULL\n", __func__);
 		return -ENODEV;
 	}
+
+	if (!vol->pcm) {
+		pr_err("%s: vol->pcm is NULL\n", __func__);
+		return -ENODEV;
+	}
+
 	substream = vol->pcm->streams[vol->stream].substream;
 	if (!substream) {
 		pr_err("%s substream not found\n", __func__);

asoc/msm-pcm-q6-v2.c

@@ -1530,6 +1530,12 @@ static int msm_pcm_volume_ctl_get(struct snd_kcontrol *kcontrol,
 		pr_err("%s: vol is NULL\n", __func__);
 		return -ENODEV;
 	}
+
+	if (!vol->pcm) {
+		pr_err("%s: vol->pcm is NULL\n", __func__);
+		return -ENODEV;
+	}
+
 	substream = vol->pcm->streams[vol->stream].substream;
 	if (!substream) {
 		pr_err("%s substream not found\n", __func__);