mceusb: fix NULL-deref at probe

BugLink: http://bugs.launchpad.net/bugs/1694621

commit 03eb2a55 upstream.

Make sure to check for the required out endpoint to avoid dereferencing
a NULL-pointer in mce_request_packet should a malicious device lack such
an endpoint. Note that this path is hit during probe.

Fixes: 66e89522 ("V4L/DVB: IR: add mceusb IR receiver driver")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

drivers/media/rc/mceusb.c

@@ -1321,8 +1321,8 @@ static int mceusb_dev_probe(struct usb_interface *intf,
 			}
 		}
 	}
-	if (ep_in == NULL) {
-		dev_dbg(&intf->dev, "inbound and/or endpoint not found");
+	if (!ep_in || !ep_out) {
+		dev_dbg(&intf->dev, "required endpoints not found\n");
 		return -ENODEV;
 	}