| Message ID | 20201007074928.GA2529578@mwanda |
|---|---|
| State | Accepted |
| Commit | b41c15f4e1c1f1657da15c482fa837c1b7384452 |
| Headers | show |
| Series | ALSA: bebob: potential info leak in hwdep_read() | expand |
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
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
On Wed, 07 Oct 2020 09:49:28 +0200, 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> Applied now. Thanks. Takashi
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);
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(-)