ip: Treat IPv4 segment's lowest address as unicast

Treat only the highest, not the lowest, IPv4 address within a local
subnet as a broadcast address.
Signed-off-by: NSeth David Schoen <schoen@loyalty.org>
Suggested-by: NJohn Gilmore <gnu@toad.com>
Acked-by: NDave Taht <dave.taht@gmail.com>
Reviewed-by: NDavid Ahern <dsahern@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/fib_frontend.c

@@ -1122,10 +1122,8 @@ void fib_add_ifaddr(struct in_ifaddr *ifa)
 				  prefix, ifa->ifa_prefixlen, prim,
 				  ifa->ifa_rt_priority);
 
-		/* Add network specific broadcasts, when it takes a sense */
+		/* Add the network broadcast address, when it makes sense */
 		if (ifa->ifa_prefixlen < 31) {
-			fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix, 32,
-				  prim, 0);
 			fib_magic(RTM_NEWROUTE, RTN_BROADCAST, prefix | ~mask,
 				  32, prim, 0);
 		}