sound: snd_ctl_remove_user_ctl: prevent removal of kernel controls

Ensure that userspace can remove only user controls.  Controls created
by kernel drivers must not be removed because they might be referenced
in calls to snd_ctl_notify().

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Clemens Ladisch 2009-08-17 12:28:09 +02:00 committed by Takashi Iwai
parent f217ac59b6
commit 18dd0aa5af

View file

@ -436,6 +436,10 @@ static int snd_ctl_remove_user_ctl(struct snd_ctl_file * file,
ret = -ENOENT;
goto error;
}
if (!(kctl->vd[0].access & SNDRV_CTL_ELEM_ACCESS_USER)) {
ret = -EINVAL;
goto error;
}
for (idx = 0; idx < kctl->count; idx++)
if (kctl->vd[idx].owner != NULL && kctl->vd[idx].owner != file) {
ret = -EBUSY;