sctp: set sin_port for addr param when checking duplicate address

Commit b8607805 ("sctp: not copying duplicate addrs to the assoc's
bind address list") tried to check for duplicate address before copying
to asoc's bind_addr list from global addr list.

But all the addrs' sin_ports in global addr list are 0 while the addrs'
sin_ports are bp->port in asoc's bind_addr list. It means even if it's
a duplicate address, af->cmp_addr will still return 0 as the their
sin_ports are different.

This patch is to fix it by setting the sin_port for addr param with
bp->port before comparing the addrs.

Fixes: b8607805 ("sctp: not copying duplicate addrs to the assoc's bind address list")
Reported-by: NWei Chen <weichen@redhat.com>
Signed-off-by: NXin Long <lucien.xin@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sctp/protocol.c

@@ -199,6 +199,7 @@ int sctp_copy_local_addr_list(struct net *net, struct sctp_bind_addr *bp,
 			      sctp_scope_t scope, gfp_t gfp, int copy_flags)
 {
 	struct sctp_sockaddr_entry *addr;
+	union sctp_addr laddr;
 	int error = 0;
 
 	rcu_read_lock();
@@ -220,7 +221,10 @@ int sctp_copy_local_addr_list(struct net *net, struct sctp_bind_addr *bp,
 		     !(copy_flags & SCTP_ADDR6_PEERSUPP)))
 			continue;
 
-		if (sctp_bind_addr_state(bp, &addr->a) != -1)
+		laddr = addr->a;
+		/* also works for setting ipv6 address port */
+		laddr.v4.sin_port = htons(bp->port);
+		if (sctp_bind_addr_state(bp, &laddr) != -1)
 			continue;
 
 		error = sctp_add_bind_addr(bp, &addr->a, sizeof(addr->a),