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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        =?UTF-8?q?Amadeusz=20S=C5=82awi=C5=84ski?= 
        <amadeuszx.slawinski@linux.intel.com>,
        Cezary Rojewski <cezary.rojewski@intel.com>,
        Takashi Iwai <tiwai@suse.de>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 011/167] ALSA: jack: Access input_dev under mutex
Date:   Mon, 13 Jun 2022 12:08:05 +0200
Message-Id: <20220613094843.460216630@linuxfoundation.org>
In-Reply-To: <20220613094840.720778945@linuxfoundation.org>
References: <20220613094840.720778945@linuxfoundation.org>
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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