dib0700: fix NULL-deref at probe

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

commit d5823511 upstream.

Make sure to check the number of endpoints to avoid dereferencing a
NULL-pointer should a malicious device lack endpoints.

Fixes: c4018fa2 ("[media] dib0700: fix RC support on Hauppauge
Nova-TD")

Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
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/usb/dvb-usb/dib0700_core.c

@@ -783,6 +783,9 @@ int dib0700_rc_setup(struct dvb_usb_device *d, struct usb_interface *intf)
 
 	/* Starting in firmware 1.20, the RC info is provided on a bulk pipe */
 
+	if (intf->altsetting[0].desc.bNumEndpoints < rc_ep + 1)
+		return -ENODEV;
+
 	purb = usb_alloc_urb(0, GFP_KERNEL);
 	if (purb == NULL) {
 		err("rc usb alloc urb failed");