staging: greybus: audio: fix uninitialized value issue

commit 1dffeb8b upstream.

The current implementation for gbcodec_mixer_dapm_ctl_put() uses
uninitialized gbvalue for comparison with updated value. This was found
using static analysis with coverity.

Uninitialized scalar variable (UNINIT)
11. uninit_use: Using uninitialized value
gbvalue.value.integer_value[0].
460        if (gbvalue.value.integer_value[0] != val) {

This patch fixes the issue with fetching the gbvalue before using it for
    comparision.

Fixes: 6339d232 ("greybus: audio: Add topology parser for GB codec")
Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Vaibhav Agarwal <vaibhav.sr@gmail.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/bc4f29eb502ccf93cd2ffd98db0e319fa7d0f247.1597408126.git.vaibhav.sr@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/greybus/audio_topology.c

@@ -462,6 +462,15 @@ static int gbcodec_mixer_dapm_ctl_put(struct snd_kcontrol *kcontrol,
 	val = ucontrol->value.integer.value[0] & mask;
 	connect = !!val;
 
+	ret = gb_pm_runtime_get_sync(bundle);
+	if (ret)
+		return ret;
+
+	ret = gb_audio_gb_get_control(module->mgmt_connection, data->ctl_id,
+				      GB_AUDIO_INVALID_INDEX, &gbvalue);
+	if (ret)
+		goto exit;
+
 	/* update ucontrol */
 	if (gbvalue.value.integer_value[0] != val) {
 		for (wi = 0; wi < wlist->num_widgets; wi++) {
@@ -475,25 +484,17 @@ static int gbcodec_mixer_dapm_ctl_put(struct snd_kcontrol *kcontrol,
 		gbvalue.value.integer_value[0] =
 			ucontrol->value.integer.value[0];
 
-		ret = gb_pm_runtime_get_sync(bundle);
-		if (ret)
-			return ret;
-
 		ret = gb_audio_gb_set_control(module->mgmt_connection,
 					      data->ctl_id,
 					      GB_AUDIO_INVALID_INDEX, &gbvalue);
-
-		gb_pm_runtime_put_autosuspend(bundle);
-
-		if (ret) {
-			dev_err_ratelimited(codec->dev,
-					    "%d:Error in %s for %s\n", ret,
-					    __func__, kcontrol->id.name);
-			return ret;
-		}
 	}
 
-	return 0;
+exit:
+	gb_pm_runtime_put_autosuspend(bundle);
+	if (ret)
+		dev_err_ratelimited(codec_dev, "%d:Error in %s for %s\n", ret,
+				    __func__, kcontrol->id.name);
+	return ret;
 }
 
 #define SOC_DAPM_MIXER_GB(xname, kcount, data) \