Patch "dccp: annotate data-races in dccp_poll()" has been added to the 5.15-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    dccp: annotate data-races in dccp_poll()

to the 5.15-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:
     dccp-annotate-data-races-in-dccp_poll.patch
and it can be found in the queue-5.15 subdirectory.

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



commit 1b118edc27df65f2f4b9ef2cae12a4d6af3a8c1c
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date:   Fri Aug 18 01:58:20 2023 +0000

    dccp: annotate data-races in dccp_poll()
    
    [ Upstream commit cba3f1786916063261e3e5ccbb803abc325b24ef ]
    
    We changed tcp_poll() over time, bug never updated dccp.
    
    Note that we also could remove dccp instead of maintaining it.
    
    Fixes: 7c657876b63c ("[DCCP]: Initial implementation")
    Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20230818015820.2701595-1-edumazet@xxxxxxxxxx
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index 5422d64af246e..0b0567a692a8f 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -324,11 +324,15 @@ EXPORT_SYMBOL_GPL(dccp_disconnect);
 __poll_t dccp_poll(struct file *file, struct socket *sock,
 		       poll_table *wait)
 {
-	__poll_t mask;
 	struct sock *sk = sock->sk;
+	__poll_t mask;
+	u8 shutdown;
+	int state;
 
 	sock_poll_wait(file, sock, wait);
-	if (sk->sk_state == DCCP_LISTEN)
+
+	state = inet_sk_state_load(sk);
+	if (state == DCCP_LISTEN)
 		return inet_csk_listen_poll(sk);
 
 	/* Socket is not locked. We are protected from async events
@@ -337,20 +341,21 @@ __poll_t dccp_poll(struct file *file, struct socket *sock,
 	 */
 
 	mask = 0;
-	if (sk->sk_err)
+	if (READ_ONCE(sk->sk_err))
 		mask = EPOLLERR;
+	shutdown = READ_ONCE(sk->sk_shutdown);
 
-	if (sk->sk_shutdown == SHUTDOWN_MASK || sk->sk_state == DCCP_CLOSED)
+	if (shutdown == SHUTDOWN_MASK || state == DCCP_CLOSED)
 		mask |= EPOLLHUP;
-	if (sk->sk_shutdown & RCV_SHUTDOWN)
+	if (shutdown & RCV_SHUTDOWN)
 		mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP;
 
 	/* Connected? */
-	if ((1 << sk->sk_state) & ~(DCCPF_REQUESTING | DCCPF_RESPOND)) {
+	if ((1 << state) & ~(DCCPF_REQUESTING | DCCPF_RESPOND)) {
 		if (atomic_read(&sk->sk_rmem_alloc) > 0)
 			mask |= EPOLLIN | EPOLLRDNORM;
 
-		if (!(sk->sk_shutdown & SEND_SHUTDOWN)) {
+		if (!(shutdown & SEND_SHUTDOWN)) {
 			if (sk_stream_is_writeable(sk)) {
 				mask |= EPOLLOUT | EPOLLWRNORM;
 			} else {  /* send SIGIO later */
@@ -368,7 +373,6 @@ __poll_t dccp_poll(struct file *file, struct socket *sock,
 	}
 	return mask;
 }
-
 EXPORT_SYMBOL_GPL(dccp_poll);
 
 int dccp_ioctl(struct sock *sk, int cmd, unsigned long arg)