Backport of lowest-address patch as submitted to OpenWRT

pending-patches/openwrt/615-v5.14-dont-treat-lowest-address-as-broadcast.patch

@@ -0,0 +1,37 @@
+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: 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(-)
+
+diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
+index 84bb707bd88d8..bfb345c88271e 100644
+--- a/net/ipv4/fib_frontend.c
++++ b/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);
+ 		}
+-- 
+cgit 
+