[PATCH 4.19 24/24] net: bridge: remove ipv6 zero address check in mcast queries

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>

commit 0fe5119e267f3e3d8ac206895f5922195ec55a8a upstream.

Recently a check was added which prevents marking of routers with zero
source address, but for IPv6 that cannot happen as the relevant RFCs
actually forbid such packets:
RFC 2710 (MLDv1):
"To be valid, the Query message MUST
 come from a link-local IPv6 Source Address, be at least 24 octets
 long, and have a correct MLD checksum."

Same goes for RFC 3810.

And also it can be seen as a requirement in ipv6_mc_check_mld_query()
which is used by the bridge to validate the message before processing
it. Thus any queries with :: source address won't be processed anyway.
So just remove the check for zero IPv6 source address from the query
processing function.

Fixes: 5a2de63fd1a5 ("bridge: do not add port to router list when receives query with source 0.0.0.0")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/bridge/br_multicast.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1426,8 +1426,7 @@ static void br_multicast_query_received(
 	 * is 0.0.0.0 should not be added to router port list.
 	 */
 	if ((saddr->proto == htons(ETH_P_IP) && saddr->u.ip4) ||
-	    (saddr->proto == htons(ETH_P_IPV6) &&
-	     !ipv6_addr_any(&saddr->u.ip6)))
+	    saddr->proto == htons(ETH_P_IPV6))
 		br_multicast_mark_router(br, port);
 }