[3.16.y-ckt stable] Patch "ASoC: soc-dapm: fix use after free" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    ASoC: soc-dapm: fix use after free

to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue

This patch is scheduled to be released in version 3.16.7-ckt2.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.16.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From bf6d3fbe3af136a563bb6ab744057be690b8b7e0 Mon Sep 17 00:00:00 2001
From: Daniel Mack <daniel at zonque.org>
Date: Tue, 7 Oct 2014 13:41:24 +0200
Subject: ASoC: soc-dapm: fix use after free

commit e5092c96c9c28f4d12811edcd02ca8eec16e748e 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 at zonque.org>
Signed-off-by: Mark Brown <broonie at kernel.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 sound/soc/soc-dapm.c | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c
index cdc837ed144d..8065fd81b40c 100644
--- a/sound/soc/soc-dapm.c
+++ b/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;

-	w->kcontrols[kci] = kcontrol;
+exit_free:
+	kfree(long_name);

-	return 0;
+	return ret;
 }

 /* create new dapm mixer control */
--
2.1.0