dccp: use READ_ONCE() to read sk->sk_bound_dev_if

When reading listener sk->sk_bound_dev_if locklessly,
we must use READ_ONCE().
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dccp/ipv4.c

@@ -628,7 +628,7 @@ int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
 	sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr);
 	ireq->ir_mark = inet_request_mark(sk, skb);
 	ireq->ireq_family = AF_INET;
-	ireq->ir_iif = sk->sk_bound_dev_if;
+	ireq->ir_iif = READ_ONCE(sk->sk_bound_dev_if);
 
 	/*
 	 * Step 3: Process LISTEN state

net/dccp/ipv6.c

@@ -374,10 +374,10 @@ static int dccp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
 		refcount_inc(&skb->users);
 		ireq->pktopts = skb;
 	}
-	ireq->ir_iif = sk->sk_bound_dev_if;
+	ireq->ir_iif = READ_ONCE(sk->sk_bound_dev_if);
 
 	/* So that link locals have meaning */
-	if (!sk->sk_bound_dev_if &&
+	if (!ireq->ir_iif &&
 	    ipv6_addr_type(&ireq->ir_v6_rmt_addr) & IPV6_ADDR_LINKLOCAL)
 		ireq->ir_iif = inet6_iif(skb);