Patch "net: annotate data-races around sk->sk_dst_pending_confirm" has been added to the 4.14-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    net: annotate data-races around sk->sk_dst_pending_confirm

to the 4.14-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:
     net-annotate-data-races-around-sk-sk_dst_pending_con.patch
and it can be found in the queue-4.14 subdirectory.

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



commit 78009963710877092a23e1d72cc3aea4de6a07bb
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date:   Thu Sep 21 20:28:18 2023 +0000

    net: annotate data-races around sk->sk_dst_pending_confirm
    
    [ Upstream commit eb44ad4e635132754bfbcb18103f1dcb7058aedd ]
    
    This field can be read or written without socket lock being held.
    
    Add annotations to avoid load-store tearing.
    
    Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/include/net/sock.h b/include/net/sock.h
index 7b42ddca4decb..f974b548e1199 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1804,7 +1804,7 @@ static inline void dst_negative_advice(struct sock *sk)
 		if (ndst != dst) {
 			rcu_assign_pointer(sk->sk_dst_cache, ndst);
 			sk_tx_queue_clear(sk);
-			sk->sk_dst_pending_confirm = 0;
+			WRITE_ONCE(sk->sk_dst_pending_confirm, 0);
 		}
 	}
 }
@@ -1815,7 +1815,7 @@ __sk_dst_set(struct sock *sk, struct dst_entry *dst)
 	struct dst_entry *old_dst;
 
 	sk_tx_queue_clear(sk);
-	sk->sk_dst_pending_confirm = 0;
+	WRITE_ONCE(sk->sk_dst_pending_confirm, 0);
 	old_dst = rcu_dereference_protected(sk->sk_dst_cache,
 					    lockdep_sock_is_held(sk));
 	rcu_assign_pointer(sk->sk_dst_cache, dst);
@@ -1828,7 +1828,7 @@ sk_dst_set(struct sock *sk, struct dst_entry *dst)
 	struct dst_entry *old_dst;
 
 	sk_tx_queue_clear(sk);
-	sk->sk_dst_pending_confirm = 0;
+	WRITE_ONCE(sk->sk_dst_pending_confirm, 0);
 	old_dst = xchg((__force struct dst_entry **)&sk->sk_dst_cache, dst);
 	dst_release(old_dst);
 }
diff --git a/net/core/sock.c b/net/core/sock.c
index 5b9f51a27dc0d..e8b5742d91492 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -534,7 +534,7 @@ struct dst_entry *__sk_dst_check(struct sock *sk, u32 cookie)
 
 	if (dst && dst->obsolete && dst->ops->check(dst, cookie) == NULL) {
 		sk_tx_queue_clear(sk);
-		sk->sk_dst_pending_confirm = 0;
+		WRITE_ONCE(sk->sk_dst_pending_confirm, 0);
 		RCU_INIT_POINTER(sk->sk_dst_cache, NULL);
 		dst_release(dst);
 		return NULL;
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 8b2d49120ce23..67636017f275a 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1059,7 +1059,7 @@ static int __tcp_transmit_skb(struct sock *sk, struct sk_buff *skb,
 	skb_set_hash_from_sk(skb, sk);
 	refcount_add(skb->truesize, &sk->sk_wmem_alloc);
 
-	skb_set_dst_pending_confirm(skb, sk->sk_dst_pending_confirm);
+	skb_set_dst_pending_confirm(skb, READ_ONCE(sk->sk_dst_pending_confirm));
 
 	/* Build TCP header and checksum it. */
 	th = (struct tcphdr *)skb->data;