[PATCH 4.9 011/167] ALSA: jack: Access input_dev under mutex

Greg Kroah-Hartman
2022-06-13T10:15:20Z

From: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>

[ Upstream commit 1b6a6fc5280e97559287b61eade2d4b363e836f2 ]

It is possible when using ASoC that input_dev is unregistered while
calling snd_jack_report, which causes NULL pointer dereference.
In order to prevent this serialize access to input_dev using mutex lock.

Signed-off-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Reviewed-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://lore.kernel.org/r/20220412091628.3056922-1-amadeuszx.slawinski@linux.intel.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/sound/jack.h | 1 +
sound/core/jack.c | 34 +++++++++++++++++++++++++++-------
2 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/include/sound/jack.h b/include/sound/jack.h
index 1e84bfb553cf..4742f842b457 100644
--- a/include/sound/jack.h
+++ b/include/sound/jack.h
@@ -77,6 +77,7 @@ struct snd_jack {
const char *id;
#ifdef CONFIG_SND_JACK_INPUT_DEV
struct input_dev *input_dev;
+ struct mutex input_dev_lock;
int registered;
int type;
char name[100];
diff --git a/sound/core/jack.c b/sound/core/jack.c
index 36cfe1c54109..d2f9a92453f2 100644
--- a/sound/core/jack.c
+++ b/sound/core/jack.c
@@ -48,8 +48,11 @@ static int snd_jack_dev_disconnect(struct snd_device *device)
#ifdef CONFIG_SND_JACK_INPUT_DEV
struct snd_jack *jack = device->device_data;

- if (!jack->input_dev)
+ mutex_lock(&jack->input_dev_lock);
+ if (!jack->input_dev) {
+ mutex_unlock(&jack->input_dev_lock);
return 0;
+ }

/* If the input device is registered with the input subsystem
* then we need to use a different deallocator. */
@@ -58,6 +61,7 @@ static int snd_jack_dev_disconnect(struct snd_device *device)
else
input_free_device(jack->input_dev);
jack->input_dev = NULL;
+ mutex_unlock(&jack->input_dev_lock);
#endif /* CONFIG_SND_JACK_INPUT_DEV */
return 0;
}
@@ -96,8 +100,11 @@ static int snd_jack_dev_register(struct snd_device *device)
snprintf(jack->name, sizeof(jack->name), "%s %s",
card->shortname, jack->id);

- if (!jack->input_dev)
+ mutex_lock(&jack->input_dev_lock);
+ if (!jack->input_dev) {
+ mutex_unlock(&jack->input_dev_lock);
return 0;
+ }

jack->input_dev->name = jack->name;

@@ -122,6 +129,7 @@ static int snd_jack_dev_register(struct snd_device *device)
if (err == 0)
jack->registered = 1;

+ mutex_unlock(&jack->input_dev_lock);
return err;
}
#endif /* CONFIG_SND_JACK_INPUT_DEV */
@@ -242,9 +250,11 @@ int snd_jack_new(struct snd_card *card, const char *id, int type,
return -ENOMEM;
}

- /* don't creat input device for phantom jack */
- if (!phantom_jack) {
#ifdef CONFIG_SND_JACK_INPUT_DEV
+ mutex_init(&jack->input_dev_lock);
+
+ /* don't create input device for phantom jack */
+ if (!phantom_jack) {
int i;

jack->input_dev = input_allocate_device();
@@ -262,8 +272,8 @@ int snd_jack_new(struct snd_card *card, const char *id, int type,
input_set_capability(jack->input_dev, EV_SW,
jack_switch_types[i]);

-#endif /* CONFIG_SND_JACK_INPUT_DEV */
}
+#endif /* CONFIG_SND_JACK_INPUT_DEV */

err = snd_device_new(card, SNDRV_DEV_JACK, jack, &ops);
if (err < 0)
@@ -303,10 +313,14 @@ EXPORT_SYMBOL(snd_jack_new);
void snd_jack_set_parent(struct snd_jack *jack, struct device *parent)
{
WARN_ON(jack->registered);
- if (!jack->input_dev)
+ mutex_lock(&jack->input_dev_lock);
+ if (!jack->input_dev) {
+ mutex_unlock(&jack->input_dev_lock);
return;
+ }

jack->input_dev->dev.parent = parent;
+ mutex_unlock(&jack->input_dev_lock);
}
EXPORT_SYMBOL(snd_jack_set_parent);

@@ -354,6 +368,8 @@ EXPORT_SYMBOL(snd_jack_set_key);

/**
* snd_jack_report - Report the current status of a jack
+ * Note: This function uses mutexes and should be called from a
+ * context which can sleep (such as a workqueue).
*
* @jack: The jack to report status for
* @status: The current status of the jack
@@ -373,8 +389,11 @@ void snd_jack_report(struct snd_jack *jack, int status)
status & jack_kctl->mask_bits);

#ifdef CONFIG_SND_JACK_INPUT_DEV
- if (!jack->input_dev)
+ mutex_lock(&jack->input_dev_lock);
+ if (!jack->input_dev) {
+ mutex_unlock(&jack->input_dev_lock);
return;
+ }

for (i = 0; i < ARRAY_SIZE(jack->key); i++) {
int testbit = SND_JACK_BTN_0 >> i;
@@ -393,6 +412,7 @@ void snd_jack_report(struct snd_jack *jack, int status)
}

input_sync(jack->input_dev);
+ mutex_unlock(&jack->input_dev_lock);
#endif /* CONFIG_SND_JACK_INPUT_DEV */
}
EXPORT_SYMBOL(snd_jack_report);
--
2.35.1