af_unix: Annotate data-races around sk->sk_state in UNIX_DIAG.

[ Upstream commit 0aa3be7 ]

While dumping AF_UNIX sockets via UNIX_DIAG, sk->sk_state is read
locklessly.

Let's use READ_ONCE() there.

Note that the result could be inconsistent if the socket is dumped
during the state change.  This is common for other SOCK_DIAG and
similar interfaces.

Fixes: c9da99e ("unix_diag: Fixup RQLEN extension report")
Fixes: 2aac7a2 ("unix_diag: Pending connections IDs NLA")
Fixes: 45a96b9 ("unix_diag: Dumping all sockets core")
Signed-off-by: Kuniyuki Iwashima <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>

net/unix/diag.c

@@ -64,7 +64,7 @@ static int sk_diag_dump_icons(struct sock *sk, struct sk_buff *nlskb)
 	u32 *buf;
 	int i;
 
-	if (sk->sk_state == TCP_LISTEN) {
+	if (READ_ONCE(sk->sk_state) == TCP_LISTEN) {
 		spin_lock(&sk->sk_receive_queue.lock);
 
 		attr = nla_reserve(nlskb, UNIX_DIAG_ICONS,
@@ -102,7 +102,7 @@ static int sk_diag_show_rqlen(struct sock *sk, struct sk_buff *nlskb)
 {
 	struct unix_diag_rqlen rql;
 
-	if (sk->sk_state == TCP_LISTEN) {
+	if (READ_ONCE(sk->sk_state) == TCP_LISTEN) {
 		rql.udiag_rqueue = sk->sk_receive_queue.qlen;
 		rql.udiag_wqueue = sk->sk_max_ack_backlog;
 	} else {
@@ -135,7 +135,7 @@ static int sk_diag_fill(struct sock *sk, struct sk_buff *skb, struct unix_diag_r
 	rep = nlmsg_data(nlh);
 	rep->udiag_family = AF_UNIX;
 	rep->udiag_type = sk->sk_type;
-	rep->udiag_state = sk->sk_state;
+	rep->udiag_state = READ_ONCE(sk->sk_state);
 	rep->pad = 0;
 	rep->udiag_ino = sk_ino;
 	sock_diag_save_cookie(sk, rep->udiag_cookie);
@@ -218,7 +218,7 @@ static int unix_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
 				continue;
 			if (num < s_num)
 				goto next;
-			if (!(req->udiag_states & (1 << sk->sk_state)))
+			if (!(req->udiag_states & (1 << READ_ONCE(sk->sk_state))))
 				goto next;
 			if (sk_diag_dump(sk, skb, req, sk_user_ns(skb->sk),
 					 NETLINK_CB(cb->skb).portid,