[ROSE]: Fix minor security hole

ROSE wasn't verifying the ndigis argument of a new route resulting in a
minor security hole.
Signed-off-by: David S. Miller <davem@davemloft.net>

net/rose/rose_route.c

@@ -727,7 +727,8 @@ int rose_rt_ioctl(unsigned int cmd, void __user *arg)
 		}
 		if (rose_route.mask > 10) /* Mask can't be more than 10 digits */
 			return -EINVAL;
-
+		if (rose_route.ndigis > 8) /* No more than 8 digipeats */
+			return -EINVAL;
 		err = rose_add_node(&rose_route, dev);
 		dev_put(dev);
 		return err;