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Commit 76b3421b authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: aloop: Add missing cable lock to ctl API callbacks 



Some control API callbacks in aloop driver are too lazy to take the
loopback->cable_lock and it results in possible races of cable access
while it's being freed.  It eventually lead to a UAF, as reported by
fuzzer recently.

This patch covers such control API callbacks and add the proper mutex
locks.

Reported-by: default avatarDaeRyong Jeong <threeearcat@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 52759c09

sound/drivers/aloop.c

+15 −2
Original line number Diff line number Diff line
@@ -831,9 +831,11 @@ static int loopback_rate_shift_get(struct snd_kcontrol *kcontrol, 
{

	struct loopback *loopback = snd_kcontrol_chip(kcontrol);

	

	mutex_lock(&loopback->cable_lock);

	ucontrol->value.integer.value[0] =

		loopback->setup[kcontrol->id.subdevice]

			       [kcontrol->id.device].rate_shift;

	mutex_unlock(&loopback->cable_lock);

	return 0;

}
@@ -865,9 +867,11 @@ static int loopback_notify_get(struct snd_kcontrol *kcontrol, 
{

	struct loopback *loopback = snd_kcontrol_chip(kcontrol);

	

	mutex_lock(&loopback->cable_lock);

	ucontrol->value.integer.value[0] =

		loopback->setup[kcontrol->id.subdevice]

			       [kcontrol->id.device].notify;

	mutex_unlock(&loopback->cable_lock);

	return 0;

}
@@ -879,12 +883,14 @@ static int loopback_notify_put(struct snd_kcontrol *kcontrol, 
	int change = 0;



	val = ucontrol->value.integer.value[0] ? 1 : 0;

	mutex_lock(&loopback->cable_lock);

	if (val != loopback->setup[kcontrol->id.subdevice]

				[kcontrol->id.device].notify) {

		loopback->setup[kcontrol->id.subdevice]

			[kcontrol->id.device].notify = val;

		change = 1;

	}

	mutex_unlock(&loopback->cable_lock);

	return change;

}
@@ -892,15 +898,18 @@ static int loopback_active_get(struct snd_kcontrol *kcontrol, 
			       struct snd_ctl_elem_value *ucontrol)

{

	struct loopback *loopback = snd_kcontrol_chip(kcontrol);

	struct loopback_cable *cable = loopback->cables

			[kcontrol->id.subdevice][kcontrol->id.device ^ 1];

	struct loopback_cable *cable;



	unsigned int val = 0;



	mutex_lock(&loopback->cable_lock);

	cable = loopback->cables[kcontrol->id.subdevice][kcontrol->id.device ^ 1];

	if (cable != NULL) {

		unsigned int running = cable->running ^ cable->pause;



		val = (running & (1 << SNDRV_PCM_STREAM_PLAYBACK)) ? 1 : 0;

	}

	mutex_unlock(&loopback->cable_lock);

	ucontrol->value.integer.value[0] = val;

	return 0;

}
@@ -943,9 +952,11 @@ static int loopback_rate_get(struct snd_kcontrol *kcontrol, 
{

	struct loopback *loopback = snd_kcontrol_chip(kcontrol);

	

	mutex_lock(&loopback->cable_lock);

	ucontrol->value.integer.value[0] =

		loopback->setup[kcontrol->id.subdevice]

			       [kcontrol->id.device].rate;

	mutex_unlock(&loopback->cable_lock);

	return 0;

}
@@ -965,9 +976,11 @@ static int loopback_channels_get(struct snd_kcontrol *kcontrol, 
{

	struct loopback *loopback = snd_kcontrol_chip(kcontrol);

	

	mutex_lock(&loopback->cable_lock);

	ucontrol->value.integer.value[0] =

		loopback->setup[kcontrol->id.subdevice]

			       [kcontrol->id.device].channels;

	mutex_unlock(&loopback->cable_lock);

	return 0;

}