USB: serial: visor: fix crash on detecting device without write_urbs

commit cb323213 upstream.

The visor driver crashes in clie_5_attach() when a specially crafted USB
device without bulk-out endpoint is detected. This fix adds a check that
the device has proper configuration expected by the driver.
Reported-by: Ralf Spenneberg <ralf@spenneberg.net>
Signed-off-by: Vladis Dronov <vdronov@redhat.com>
Fixes: cfb8da8f ("USB: visor: fix initialisation of UX50/TH55 devices")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/usb/serial/visor.c

@@ -640,8 +640,10 @@ static int clie_5_attach(struct usb_serial *serial)
 	 */
 
 	/* some sanity check */
-	if (serial->num_ports < 2)
-		return -1;
+	if (serial->num_bulk_out < 2) {
+		dev_err(&serial->interface->dev, "missing bulk out endpoints\n");
+		return -ENODEV;
+	}
 
 	/* port 0 now uses the modified endpoint Address */
 	port = serial->port[0];