Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.16 08/52] ALSA: aloop: Add missing cable lock to ctl API callbacks | Date | Tue, 8 May 2018 10:10:06 +0200 |
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4.16-stable review patch. If anyone has any objections, please let me know.
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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 @@ -831,9 +831,11 @@ 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; } @@ -865,9 +867,11 @@ 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; } @@ -879,12 +883,14 @@ 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; } @@ -892,15 +898,18 @@ 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; } @@ -943,9 +952,11 @@ 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; } @@ -965,9 +976,11 @@ 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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