[PATCH 4.4 039/113] ASoC: dapm: Fix potential DAI widget pointer deref when linking DAIs

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Liam Girdwood <liam.r.girdwood@xxxxxxxxxxxxxxx>

[ Upstream commit e01b4f624278d5efe5fb5da585ca371947b16680 ]

Sometime a component or topology may configure a DAI widget with no
private data leading to a dev_dbg() dereferencne of this data.

Fix this to check for non NULL private data and let users know if widget
is missing DAI.

Signed-off-by: Liam Girdwood <liam.r.girdwood@xxxxxxxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 sound/soc/soc-dapm.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/sound/soc/soc-dapm.c
+++ b/sound/soc/soc-dapm.c
@@ -3864,6 +3864,13 @@ int snd_soc_dapm_link_dai_widgets(struct
 			continue;
 		}
 
+		/* let users know there is no DAI to link */
+		if (!dai_w->priv) {
+			dev_dbg(card->dev, "dai widget %s has no DAI\n",
+				dai_w->name);
+			continue;
+		}
+
 		dai = dai_w->priv;
 
 		/* ...find all widgets with the same stream and link them */