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

Kamal Mostafa
2014-10-27T19:05:19Z

From: Daniel Mack <daniel@zonque.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@zonque.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@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 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