[media] usbtv: correctly handling failed allocation

Since kzalloc can be failed,
if not properly handled, NULL dereference could be happened.
Signed-off-by: NInsu Yun <wuninsu@gmail.com>
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/usb/usbtv/usbtv-video.c

@@ -393,6 +393,10 @@ static struct urb *usbtv_setup_iso_transfer(struct usbtv *usbtv)
 	ip->transfer_flags = URB_ISO_ASAP;
 	ip->transfer_buffer = kzalloc(size * USBTV_ISOC_PACKETS,
 						GFP_KERNEL);
+	if (!ip->transfer_buffer) {
+		usb_free_urb(ip);
+		return NULL;
+	}
 	ip->complete = usbtv_iso_cb;
 	ip->number_of_packets = USBTV_ISOC_PACKETS;
 	ip->transfer_buffer_length = size * USBTV_ISOC_PACKETS;