ASoC: Fix use after free

Freeing the current list element while iterating over the list will cause a use
after free since the iterator function will still use the current element to
look up the next. Use list_for_each_safe() and remove the element from the list
before freeing it to avoid this.

Fixes: 1438c2f6 ("ASoC: Add a per component dai list")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/soc-core.c

@@ -3913,11 +3913,12 @@ static inline char *fmt_multiple_name(struct device *dev,
  */
 static void snd_soc_unregister_dais(struct snd_soc_component *component)
 {
-	struct snd_soc_dai *dai;
+	struct snd_soc_dai *dai, *_dai;
 
-	list_for_each_entry(dai, &component->dai_list, list) {
+	list_for_each_entry_safe(dai, _dai, &component->dai_list, list) {
 		dev_dbg(component->dev, "ASoC: Unregistered DAI '%s'\n",
 			dai->name);
+		list_del(&dai->list);
 		kfree(dai->name);
 		kfree(dai);
 	}