inet: don't use sk_v6_rcv_saddr directly

When comparing two sockets we need to use inet6_rcv_saddr so we get a NULL
sk_v6_rcv_saddr if the socket isn't AF_INET6, otherwise our comparison function
can be wrong.

Fixes: 637bc8bb ("inet: reset tb->fastreuseport when adding a reuseport sk")
Signed-off-by: NJosef Bacik <jbacik@fb.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/inet_connection_sock.c

@@ -99,7 +99,7 @@ int inet_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2,
 #if IS_ENABLED(CONFIG_IPV6)
 	if (sk->sk_family == AF_INET6)
 		return ipv6_rcv_saddr_equal(&sk->sk_v6_rcv_saddr,
-					    &sk2->sk_v6_rcv_saddr,
+					    inet6_rcv_saddr(sk2),
 					    sk->sk_rcv_saddr,
 					    sk2->sk_rcv_saddr,
 					    ipv6_only_sock(sk),