Use the copy_from_user() and copy_to_user() functions for accessing
memory provided by the user in the ptm netdev iotls.
In addition also check for root permission before executing ioctl.
Suggested-by: Stanislav Fort from Aisle Research
Reported-by: Stanislav Fort from Aisle Research
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
(cherry picked from commit 2a76abc5442e3f74d95b4caa9bb57e5488fc132e)
(cherry picked from commit e001b31163a77683ee741d169f794cfa50926f37)
71e1563983