ASoC: soc-dapm: fix use after free

commit e5092c96 upstream.

Coverity spotted the following possible use-after-free condition in
dapm_create_or_share_mixmux_kcontrol():

If kcontrol is NULL, and (wname_in_long_name && kcname_in_long_name)
validates to true, 'name' will be set to an allocated string, and be
freed a few lines later via the 'long_name' alias. 'name', however,
is used by dev_err() in case snd_ctl_add() fails.

Fix this by adding a jump label that frees 'long_name' at the end of
the function.
Signed-off-by: Daniel Mack <daniel@zonque.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

sound/soc/soc-dapm.c

@@ -566,9 +566,9 @@ static int dapm_create_or_share_mixmux_kcontrol(struct snd_soc_dapm_widget *w,
 	int shared;
 	struct snd_kcontrol *kcontrol;
 	bool wname_in_long_name, kcname_in_long_name;
-	char *long_name;
+	char *long_name = NULL;
 	const char *name;
-	int ret;
+	int ret = 0;
 
 	if (dapm->codec)
 		prefix = dapm->codec->name_prefix;
@@ -631,15 +631,17 @@ static int dapm_create_or_share_mixmux_kcontrol(struct snd_soc_dapm_widget *w,
 
 		kcontrol = snd_soc_cnew(&w->kcontrol_news[kci], NULL, name,
 					prefix);
-		kfree(long_name);
-		if (!kcontrol)
-			return -ENOMEM;
+		if (!kcontrol) {
+			ret = -ENOMEM;
+			goto exit_free;
+		}
+
 		kcontrol->private_free = dapm_kcontrol_free;
 
 		ret = dapm_kcontrol_data_alloc(w, kcontrol);
 		if (ret) {
 			snd_ctl_free_one(kcontrol);
-			return ret;
+			goto exit_free;
 		}
 
 		ret = snd_ctl_add(card, kcontrol);
@@ -647,17 +649,18 @@ static int dapm_create_or_share_mixmux_kcontrol(struct snd_soc_dapm_widget *w,
 			dev_err(dapm->dev,
 				"ASoC: failed to add widget %s dapm kcontrol %s: %d\n",
 				w->name, name, ret);
-			return ret;
+			goto exit_free;
 		}
 	}
 
 	ret = dapm_kcontrol_add_widget(kcontrol, w);
-	if (ret)
-		return ret;
-
+	if (ret == 0)
 		w->kcontrols[kci] = kcontrol;
 
-	return 0;
+exit_free:
+	kfree(long_name);
+
+	return ret;
 }
 
 /* create new dapm mixer control */