USB: fix out-of-bounds in usb_set_configuration

USB: fix out-of-bounds in usb_set_configuration

Andrey Konovalov reported a possible out-of-bounds problem for a USB interface
association descriptor.  He writes:
	It seems there's no proper size check of a USB_DT_INTERFACE_ASSOCIATION
	descriptor. It's only checked that the size is >= 2 in
	usb_parse_configuration(), so find_iad() might do out-of-bounds access
	to intf_assoc->bInterfaceCount.

And he's right, we don't check for crazy descriptors of this type very well, so
resolve this problem.  Yet another issue found by syzkaller...

Reported-by: Andrey Konovalov <andreyknvl@google.com>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit bd7a3fe770ebd8391d1c7d072ff88e9e76d063eb)

Orabug: 27207211
CVE: CVE-2017-16531

Signed-off-by: Tim Tianyang Chen <tianyang.chen@oracle.com>
Reviewed-by: Reviewed-by: Jack Vogel <jack.vogel@oracle.com>