Oops, I forgot to add my tag to the former message.

Acked-by: Takashi Sakamoto o-takashi@sakamocchi.jp

On Wed, Oct 07, 2020 at 10:04:37PM +0900, Takashi Sakamoto wrote:

Hi,

Thanks for the patch.

On Wed, Oct 07, 2020 at 10:49:28AM +0300, Dan Carpenter wrote:

...

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@oracle.com

---

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

diff --git a/sound/firewire/bebob/bebob_hwdep.c b/sound/firewire/bebob/bebob_hwdep.c index 45b740f44c45..c362eb38ab90 100644 --- a/sound/firewire/bebob/bebob_hwdep.c +++ b/sound/firewire/bebob/bebob_hwdep.c @@ -36,12 +36,11 @@ hwdep_read(struct snd_hwdep *hwdep, char __user *buf, long count, }

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);

-- 2.28.0

Indeed, the bug can leak the contents of kernel memory into user space unintentionally for the size indicated by ALSA HwDep application...

I will check the other drivers in ALSA firewire stack later for safe.

Thanks

Takashi Sakamoto