linux-kernel - [PATCH 3.13 079/105] ASoC: soc-dapm: fix use after free

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Message-Id: <1414436240-13879-80-git-send-email-kamal@canonical.com>
Date:	Mon, 27 Oct 2014 11:56:54 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Daniel Mack <daniel@...que.org>, Mark Brown <broonie@...nel.org>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.13 079/105] ASoC: soc-dapm: fix use after free

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

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

From: Daniel Mack <daniel@...que.org>

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@...que.org>
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Kamal Mostafa <kamal@...onical.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 2e6f4ec..2a9b542 100644
--- a/sound/soc/soc-dapm.c
+++ b/sound/soc/soc-dapm.c
@@ -686,9 +686,9 @@ 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;
@@ -753,15 +753,17 @@ 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);
@@ -769,17 +771,18 @@ 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 */
-- 
1.9.1

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