From 94c821c74bf5fe0c25e09df5334a16f98608db90 Mon Sep 17 00:00:00 2001
From: Seth David Schoen <schoen@loyalty.org>
Date: Wed, 12 May 2021 21:37:49 -0700
Subject: [PATCH] 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: Seth David Schoen <schoen@loyalty.org>
Suggested-by: John Gilmore <gnu@toad.com>
Acked-by: Dave Taht <dave.taht@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Link: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=94c821c74bf5
---
 net/ipv4/fib_frontend.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -1129,10 +1129,8 @@ void fib_add_ifaddr(struct in_ifaddr *if
 				  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);
 			arp_invalidate(dev, prefix | ~mask, false);