af_unix: Annotate data-race of sk->sk_state in unix_stream_read_skb().

unix_stream_read_skb() is called from sk->sk_data_ready() context
where unix_state_lock() is not held.

Let's use READ_ONCE() there.

Fixes: 77462de1 ("af_unix: Add read_sock for stream socket types")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

net/unix/af_unix.c

@@ -2659,7 +2659,7 @@ static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
 
 static int unix_stream_read_skb(struct sock *sk, skb_read_actor_t recv_actor)
 {
-	if (unlikely(sk->sk_state != TCP_ESTABLISHED))
+	if (unlikely(READ_ONCE(sk->sk_state) != TCP_ESTABLISHED))
 		return -ENOTCONN;
 
 	return unix_read_skb(sk, recv_actor);