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Subject[PATCH 4.14 12/43] ALSA: aloop: Add missing cable lock to ctl API callbacks
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

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

From: Takashi Iwai <tiwai@suse.de>

commit 76b3421b39bd610546931fc923edcf90c18fa395 upstream.

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: DaeRyong Jeong <threeearcat@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
sound/drivers/aloop.c | 17 +++++++++++++++--
1 file changed, 15 insertions(+), 2 deletions(-)

--- a/sound/drivers/aloop.c
+++ b/sound/drivers/aloop.c
@@ -832,9 +832,11 @@ static int loopback_rate_shift_get(struc
{
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;
}

@@ -866,9 +868,11 @@ static int loopback_notify_get(struct sn
{
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;
}

@@ -880,12 +884,14 @@ static int loopback_notify_put(struct sn
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;
}

@@ -893,15 +899,18 @@ static int loopback_active_get(struct sn
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;
}
@@ -944,9 +953,11 @@ static int loopback_rate_get(struct snd_
{
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;
}

@@ -966,9 +977,11 @@ static int loopback_channels_get(struct
{
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;
}


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