An attack using the lack of sanity checking in probe is known. This
patch checks for the existence of a second port.

CVE-2016-3136
Signed-off-by: NOliver Neukum <ONeukum@suse.com>
CC: stable@vger.kernel.org
[johan: add error message ]
Signed-off-by: NJohan Hovold <johan@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>