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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: DaeRyong Jeong <threeearcat@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2018-04-30 10:06:48 +02:00
parent 52759c0963
commit 76b3421b39
1 changed files with 15 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
sound/drivers/aloop.c
View File

@ -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;
}