release/5.2.53/ipv6-Fix-use-of-anycast-address-with-loopback.patch

From f4bee498b191376e55bb82a6670d02a272243a1a Mon Sep 17 00:00:00 2001
From: David Ahern <dsahern@kernel.org>
Date: Tue, 7 Jul 2020 07:39:24 -0600
Subject: [PATCH] ipv6: Fix use of anycast address with loopback

commit aea23c323d89836bcdcee67e49def997ffca043b upstream.

Thomas reported a regression with IPv6 and anycast using the following
reproducer:

    echo 1 >  /proc/sys/net/ipv6/conf/all/forwarding
    ip -6 a add fc12::1/16 dev lo
    sleep 2
    echo "pinging lo"
    ping6 -c 2 fc12::

The conversion of addrconf_f6i_alloc to use ip6_route_info_create missed
the use of fib6_is_reject which checks addresses added to the loopback
interface and sets the REJECT flag as needed. Update fib6_is_reject for
loopback checks to handle RTF_ANYCAST addresses.

Fixes: c7a1ce397ada ("ipv6: Change addrconf_f6i_alloc to use ip6_route_info_create")
Reported-by: thomas.gambier@nexedi.com
Signed-off-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 1f5a33d0c68c..a71b115e65fe 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -2989,7 +2989,7 @@ static bool fib6_is_reject(u32 flags, struct net_device *dev, int addr_type)
 	if ((flags & RTF_REJECT) ||
 	    (dev && (dev->flags & IFF_LOOPBACK) &&
 	     !(addr_type & IPV6_ADDR_LOOPBACK) &&
-	     !(flags & RTF_LOCAL)))
+	     !(flags & (RTF_ANYCAST | RTF_LOCAL))))
 		return true;
 
 	return false;
-- 
2.27.0