ASoC: dapm: Lock during userspace access

[ Upstream commit d90d066 ]

commit e50b1e0 upstream.

The DAPM lock must be held when accessing the DAPM graph status through
sysfs or debugfs, otherwise concurrent changes to the graph can result in
undefined behaviour.

Signed-off-by: Lars-Peter Clausen <[email protected]>
Signed-off-by: Mark Brown <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>

sound/soc/soc-dapm.c

@@ -1854,6 +1854,7 @@ static ssize_t dapm_widget_power_read_file(struct file *file,
 					   size_t count, loff_t *ppos)
 {
 	struct snd_soc_dapm_widget *w = file->private_data;
+	struct snd_soc_card *card = w->dapm->card;
 	char *buf;
 	int in, out;
 	ssize_t ret;
@@ -1863,6 +1864,8 @@ static ssize_t dapm_widget_power_read_file(struct file *file,
 	if (!buf)
 		return -ENOMEM;
 
+	mutex_lock(&card->dapm_mutex);
+
 	in = is_connected_input_ep(w, NULL);
 	dapm_clear_walk_input(w->dapm, &w->sources);
 	out = is_connected_output_ep(w, NULL);
@@ -1905,6 +1908,8 @@ static ssize_t dapm_widget_power_read_file(struct file *file,
 					p->sink->name);
 	}
 
+	mutex_unlock(&card->dapm_mutex);
+
 	ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);
 
 	kfree(buf);
@@ -2165,11 +2170,15 @@ static ssize_t dapm_widget_show(struct device *dev,
 	struct snd_soc_pcm_runtime *rtd = dev_get_drvdata(dev);
 	int i, count = 0;
 
+	mutex_lock(&rtd->card->dapm_mutex);
+
 	for (i = 0; i < rtd->num_codecs; i++) {
 		struct snd_soc_codec *codec = rtd->codec_dais[i]->codec;
 		count += dapm_widget_show_codec(codec, buf + count);
 	}
 
+	mutex_unlock(&rtd->card->dapm_mutex);
+
 	return count;
 }