Patch "af_unix: Annodate data-races around sk->sk_state for writers." has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    af_unix: Annodate data-races around sk->sk_state for writers.

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     af_unix-annodate-data-races-around-sk-sk_state-for-w.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 7396984c57611b2d5fa829452d2a13999a574330
Author: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Date:   Tue Jun 4 09:52:28 2024 -0700

    af_unix: Annodate data-races around sk->sk_state for writers.
    
    [ Upstream commit 942238f9735a4a4ebf8274b218d9a910158941d1 ]
    
    sk->sk_state is changed under unix_state_lock(), but it's read locklessly
    in many places.
    
    This patch adds WRITE_ONCE() on the writer side.
    
    We will add READ_ONCE() to the lockless readers in the following patches.
    
    Fixes: 83301b5367a9 ("af_unix: Set TCP_ESTABLISHED for datagram sockets too")
    Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
    Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
    Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 348f9e34f6696..bd2af62f58605 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -617,7 +617,7 @@ static void unix_release_sock(struct sock *sk, int embrion)
 	u->path.dentry = NULL;
 	u->path.mnt = NULL;
 	state = sk->sk_state;
-	sk->sk_state = TCP_CLOSE;
+	WRITE_ONCE(sk->sk_state, TCP_CLOSE);
 
 	skpair = unix_peer(sk);
 	unix_peer(sk) = NULL;
@@ -739,7 +739,8 @@ static int unix_listen(struct socket *sock, int backlog)
 	if (backlog > sk->sk_max_ack_backlog)
 		wake_up_interruptible_all(&u->peer_wait);
 	sk->sk_max_ack_backlog	= backlog;
-	sk->sk_state		= TCP_LISTEN;
+	WRITE_ONCE(sk->sk_state, TCP_LISTEN);
+
 	/* set credentials so connect can copy them */
 	init_peercred(sk);
 	err = 0;
@@ -1411,7 +1412,8 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
 		if (err)
 			goto out_unlock;
 
-		sk->sk_state = other->sk_state = TCP_ESTABLISHED;
+		WRITE_ONCE(sk->sk_state, TCP_ESTABLISHED);
+		WRITE_ONCE(other->sk_state, TCP_ESTABLISHED);
 	} else {
 		/*
 		 *	1003.1g breaking connected state with AF_UNSPEC
@@ -1428,7 +1430,7 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
 
 		unix_peer(sk) = other;
 		if (!other)
-			sk->sk_state = TCP_CLOSE;
+			WRITE_ONCE(sk->sk_state, TCP_CLOSE);
 		unix_dgram_peer_wake_disconnect_wakeup(sk, old_peer);
 
 		unix_state_double_unlock(sk, other);
@@ -1644,7 +1646,7 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 	copy_peercred(sk, other);
 
 	sock->state	= SS_CONNECTED;
-	sk->sk_state	= TCP_ESTABLISHED;
+	WRITE_ONCE(sk->sk_state, TCP_ESTABLISHED);
 	sock_hold(newsk);
 
 	smp_mb__after_atomic();	/* sock_hold() does an atomic_inc() */
@@ -2027,7 +2029,7 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 			unix_peer(sk) = NULL;
 			unix_dgram_peer_wake_disconnect_wakeup(sk, other);
 
-			sk->sk_state = TCP_CLOSE;
+			WRITE_ONCE(sk->sk_state, TCP_CLOSE);
 			unix_state_unlock(sk);
 
 			unix_dgram_disconnected(sk, other);