USB: visor: fix null-deref at probe

commit cac9b50b upstream.

Fix null-pointer dereference at probe should a (malicious) Treo device
lack the expected endpoints.

Specifically, the Treo port-setup hack was dereferencing the bulk-in and
interrupt-in urbs without first making sure they had been allocated by
core.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/usb/serial/visor.c

@@ -544,6 +544,11 @@ static int treo_attach(struct usb_serial *serial)
 		(serial->num_interrupt_in == 0))
 		return 0;
 
+	if (serial->num_bulk_in < 2 || serial->num_interrupt_in < 2) {
+		dev_err(&serial->interface->dev, "missing endpoints\n");
+		return -ENODEV;
+	}
+
 	/*
 	* It appears that Treos and Kyoceras want to use the
 	* 1st bulk in endpoint to communicate with the 2nd bulk out endpoint,