From: Lars-Peter Clausen <lars@metafoo.de>
Date: Thu, 1 Aug 2013 16:30:38 +0000 (+0200)
Subject: ASoC: dapm: Fix empty list check in dapm_new_mux()
X-Git-Tag: v3.10.8~26
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=4bd3f15b77578866fda9b0da4ef027f06ed3b746;p=platform%2Fkernel%2Flinux-stable.git

ASoC: dapm: Fix empty list check in dapm_new_mux()

commit fe581391147cb3d738d961d0f1233d91a9e1113c upstream.

list_first_entry() will always return a valid pointer, even if the list is
empty. So the check whether path is NULL will always be false. So we end up
calling dapm_create_or_share_mixmux_kcontrol() with a path struct that points
right in the middle of the widget struct and by trying to modify the path the
widgets memory will become corrupted. Fix this by using list_emtpy() to check if
the widget doesn't have any paths.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Tested-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c
index c7051c4..3606383 100644
--- a/sound/soc/soc-dapm.c
+++ b/sound/soc/soc-dapm.c
@@ -682,13 +682,14 @@ static int dapm_new_mux(struct snd_soc_dapm_widget *w)
 		return -EINVAL;
 	}
 
-	path = list_first_entry(&w->sources, struct snd_soc_dapm_path,
-				list_sink);
-	if (!path) {
+	if (list_empty(&w->sources)) {
 		dev_err(dapm->dev, "ASoC: mux %s has no paths\n", w->name);
 		return -EINVAL;
 	}
 
+	path = list_first_entry(&w->sources, struct snd_soc_dapm_path,
+				list_sink);
+
 	ret = dapm_create_or_share_mixmux_kcontrol(w, 0, path);
 	if (ret < 0)
 		return ret;