USB: mct_u232: add sanity checking in probe

USB: mct_u232: add sanity checking in probe

Orabug: 23331165

[ Upstream commit 4e9a0b05257f29cf4b75f3209243ed71614d062e ]

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: Oliver Neukum <ONeukum@suse.com>
CC: stable@vger.kernel.org
[johan: add error message ]
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
(cherry picked from commit 4b8d00f5056e278b053ca183e15f4a8e48d79336)

Signed-off-by: Dan Duval <dan.duval@oracle.com>