[PATCH 4.19 015/264] ALSA: bebob: potential info leak in hwdep_read()

From: Greg Kroah-Hartman
Date: Tue Oct 27 2020 - 10:20:38 EST


From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

commit b41c15f4e1c1f1657da15c482fa837c1b7384452 upstream.

The "count" variable needs to be capped on every path so that we don't
copy too much information to the user.

Fixes: 618eabeae711 ("ALSA: bebob: Add hwdep interface")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Acked-by: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20201007074928.GA2529578@mwanda
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
sound/firewire/bebob/bebob_hwdep.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

--- a/sound/firewire/bebob/bebob_hwdep.c
+++ b/sound/firewire/bebob/bebob_hwdep.c
@@ -37,12 +37,11 @@ hwdep_read(struct snd_hwdep *hwdep, char
}

memset(&event, 0, sizeof(event));
+ count = min_t(long, count, sizeof(event.lock_status));
if (bebob->dev_lock_changed) {
event.lock_status.type = SNDRV_FIREWIRE_EVENT_LOCK_STATUS;
event.lock_status.status = (bebob->dev_lock_count > 0);
bebob->dev_lock_changed = false;
-
- count = min_t(long, count, sizeof(event.lock_status));
}

spin_unlock_irq(&bebob->lock);