[PATCH net] net: annotate data-races around sk->sk_{data_ready,write_space}

[PATCH net] net: annotate data-races around sk->sk_{data_ready,write_space}

[Eric Dumazet]

skmsg (and probably other layers) are changing these pointers
while other cpus might read them concurrently.

Add corresponding READ_ONCE()/WRITE_ONCE() annotations
for UDP, TCP and AF_UNIX.

Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
Reported-by: syzbot+87f770387a9e5dc6b79b@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/netdev/699ee9fc.050a0220.1cd54b.0009.GAE@google.com/
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Kuniyuki Iwashima <kuniyu@google.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
---
 net/core/skmsg.c         | 14 +++++++-------
 net/ipv4/tcp.c           |  4 ++--
 net/ipv4/tcp_bpf.c       |  2 +-
 net/ipv4/tcp_input.c     | 14 ++++++++------
 net/ipv4/tcp_minisocks.c |  2 +-
 net/ipv4/udp.c           |  2 +-
 net/ipv4/udp_bpf.c       |  2 +-
 net/unix/af_unix.c       |  8 ++++----
 8 files changed, 25 insertions(+), 23 deletions(-)

diff --git a/net/core/skmsg.c b/net/core/skmsg.c
index ddde93dd8bc6d4e7941daff8b18229376f0d459d..12fbb0545c7123373de4581838debaf9a6c1f870 100644
--- a/net/core/skmsg.c
+++ b/net/core/skmsg.c
@@ -1205,8 +1205,8 @@ void sk_psock_start_strp(struct sock *sk, struct sk_psock *psock)
 		return;
 
 	psock->saved_data_ready = sk->sk_data_ready;
-	sk->sk_data_ready = sk_psock_strp_data_ready;
-	sk->sk_write_space = sk_psock_write_space;
+	WRITE_ONCE(sk->sk_data_ready, sk_psock_strp_data_ready);
+	WRITE_ONCE(sk->sk_write_space, sk_psock_write_space);
 }
 
 void sk_psock_stop_strp(struct sock *sk, struct sk_psock *psock)
@@ -1216,8 +1216,8 @@ void sk_psock_stop_strp(struct sock *sk, struct sk_psock *psock)
 	if (!psock->saved_data_ready)
 		return;
 
-	sk->sk_data_ready = psock->saved_data_ready;
-	psock->saved_data_ready = NULL;
+	WRITE_ONCE(sk->sk_data_ready, psock->saved_data_ready);
+	WRITE_ONCE(psock->saved_data_ready, NULL);
 	strp_stop(&psock->strp);
 }
 
@@ -1296,8 +1296,8 @@ void sk_psock_start_verdict(struct sock *sk, struct sk_psock *psock)
 		return;
 
 	psock->saved_data_ready = sk->sk_data_ready;
-	sk->sk_data_ready = sk_psock_verdict_data_ready;
-	sk->sk_write_space = sk_psock_write_space;
+	WRITE_ONCE(sk->sk_data_ready, sk_psock_verdict_data_ready);
+	WRITE_ONCE(sk->sk_write_space, sk_psock_write_space);
 }
 
 void sk_psock_stop_verdict(struct sock *sk, struct sk_psock *psock)
@@ -1308,6 +1308,6 @@ void sk_psock_stop_verdict(struct sock *sk, struct sk_psock *psock)
 	if (!psock->saved_data_ready)
 		return;
 
-	sk->sk_data_ready = psock->saved_data_ready;
+	WRITE_ONCE(sk->sk_data_ready, psock->saved_data_ready);
 	psock->saved_data_ready = NULL;
 }
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 6ce03a9adb4a97f554bd6b6cf887f4ad9dbfe5c3..1153780945ab369c45bef6b740c8e87c8bae4ea3 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1446,7 +1446,7 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
 	err = sk_stream_error(sk, flags, err);
 	/* make sure we wake any epoll edge trigger waiter */
 	if (unlikely(tcp_rtx_and_write_queues_empty(sk) && err == -EAGAIN)) {
-		sk->sk_write_space(sk);
+		READ_ONCE(sk->sk_write_space)(sk);
 		tcp_chrono_stop(sk, TCP_CHRONO_SNDBUF_LIMITED);
 	}
 	if (binding)
@@ -4181,7 +4181,7 @@ int do_tcp_setsockopt(struct sock *sk, int level, int optname,
 		break;
 	case TCP_NOTSENT_LOWAT:
 		WRITE_ONCE(tp->notsent_lowat, val);
-		sk->sk_write_space(sk);
+		READ_ONCE(sk->sk_write_space)(sk);
 		break;
 	case TCP_INQ:
 		if (val > 1 || val < 0)
diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index ca8a5cb8e569d78d7b1df03eb904ac5cc115cf47..d3d6a47af5270178b4dfe2a158c61090a948f4e0 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -725,7 +725,7 @@ int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
 			WRITE_ONCE(sk->sk_prot->unhash, psock->saved_unhash);
 			tcp_update_ulp(sk, psock->sk_proto, psock->saved_write_space);
 		} else {
-			sk->sk_write_space = psock->saved_write_space;
+			WRITE_ONCE(sk->sk_write_space, psock->saved_write_space);
 			/* Pairs with lockless read in sk_clone_lock() */
 			sock_replace_proto(sk, psock->sk_proto);
 		}
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index e7b41abb82aad33d8cab4fcfa989cc4771149b41..2e7bea7fe8cab23e80458c78e3edd81f33ee4b2b 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5416,7 +5416,7 @@ static void tcp_data_queue_ofo(struct sock *sk, struct sk_buff *skb)
 
 	if (unlikely(tcp_try_rmem_schedule(sk, skb, skb->truesize))) {
 		NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPOFODROP);
-		sk->sk_data_ready(sk);
+		READ_ONCE(sk->sk_data_ready)(sk);
 		tcp_drop_reason(sk, skb, SKB_DROP_REASON_PROTO_MEM);
 		return;
 	}
@@ -5626,7 +5626,7 @@ int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size)
 void tcp_data_ready(struct sock *sk)
 {
 	if (tcp_epollin_ready(sk, sk->sk_rcvlowat) || sock_flag(sk, SOCK_DONE))
-		sk->sk_data_ready(sk);
+		READ_ONCE(sk->sk_data_ready)(sk);
 }
 
 static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
@@ -5682,7 +5682,7 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb)
 			inet_csk(sk)->icsk_ack.pending |=
 					(ICSK_ACK_NOMEM | ICSK_ACK_NOW);
 			inet_csk_schedule_ack(sk);
-			sk->sk_data_ready(sk);
+			READ_ONCE(sk->sk_data_ready)(sk);
 
 			if (skb_queue_len(&sk->sk_receive_queue) && skb->len) {
 				reason = SKB_DROP_REASON_PROTO_MEM;
@@ -6105,7 +6105,9 @@ static void tcp_new_space(struct sock *sk)
 		tp->snd_cwnd_stamp = tcp_jiffies32;
 	}
 
-	INDIRECT_CALL_1(sk->sk_write_space, sk_stream_write_space, sk);
+	INDIRECT_CALL_1(READ_ONCE(sk->sk_write_space),
+			sk_stream_write_space,
+			sk);
 }
 
 /* Caller made space either from:
@@ -6316,7 +6318,7 @@ static void tcp_urg(struct sock *sk, struct sk_buff *skb, const struct tcphdr *t
 				BUG();
 			WRITE_ONCE(tp->urg_data, TCP_URG_VALID | tmp);
 			if (!sock_flag(sk, SOCK_DEAD))
-				sk->sk_data_ready(sk);
+				READ_ONCE(sk->sk_data_ready)(sk);
 		}
 	}
 }
@@ -7783,7 +7785,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
 			sock_put(fastopen_sk);
 			goto drop_and_free;
 		}
-		sk->sk_data_ready(sk);
+		READ_ONCE(sk->sk_data_ready)(sk);
 		bh_unlock_sock(fastopen_sk);
 		sock_put(fastopen_sk);
 	} else {
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index d9c5a43bd2818c17d79d8433ac5dd2bdd199b812..dafb63b923d0d08cb1a0e9a37d8ec025386a960a 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -1004,7 +1004,7 @@ enum skb_drop_reason tcp_child_process(struct sock *parent, struct sock *child,
 		reason = tcp_rcv_state_process(child, skb);
 		/* Wakeup parent, send SIGIO */
 		if (state == TCP_SYN_RECV && child->sk_state != state)
-			parent->sk_data_ready(parent);
+			READ_ONCE(parent->sk_data_ready)(parent);
 	} else {
 		/* Alas, it is possible again, because we do lookup
 		 * in main socket hash table and lock on listening
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index b96e47f1c8a2a92296acc0a9c724019c44c097ea..422c96fea2493247910e9ea11f3cda03833c5c33 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1787,7 +1787,7 @@ int __udp_enqueue_schedule_skb(struct sock *sk, struct sk_buff *skb)
 		 * using prepare_to_wait_exclusive().
 		 */
 		while (nb) {
-			INDIRECT_CALL_1(sk->sk_data_ready,
+			INDIRECT_CALL_1(READ_ONCE(sk->sk_data_ready),
 					sock_def_readable, sk);
 			nb--;
 		}
diff --git a/net/ipv4/udp_bpf.c b/net/ipv4/udp_bpf.c
index 91233e37cd97a2b0f0c891723b20b1235cc628d1..779a3a03762f1e3ff4da40597c9e4d7a7a4f04d6 100644
--- a/net/ipv4/udp_bpf.c
+++ b/net/ipv4/udp_bpf.c
@@ -158,7 +158,7 @@ int udp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
 	int family = sk->sk_family == AF_INET ? UDP_BPF_IPV4 : UDP_BPF_IPV6;
 
 	if (restore) {
-		sk->sk_write_space = psock->saved_write_space;
+		WRITE_ONCE(sk->sk_write_space, psock->saved_write_space);
 		sock_replace_proto(sk, psock->sk_proto);
 		return 0;
 	}
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index f6d56e70c7a2c387fda6d06f30653cd662463f39..6965b9a49d68a28c688992e3cf09dbdbe80b9c59 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1785,7 +1785,7 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr_unsized *uad
 	__skb_queue_tail(&other->sk_receive_queue, skb);
 	spin_unlock(&other->sk_receive_queue.lock);
 	unix_state_unlock(other);
-	other->sk_data_ready(other);
+	READ_ONCE(other->sk_data_ready)(other);
 	sock_put(other);
 	return 0;
 
@@ -2278,7 +2278,7 @@ static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
 	scm_stat_add(other, skb);
 	skb_queue_tail(&other->sk_receive_queue, skb);
 	unix_state_unlock(other);
-	other->sk_data_ready(other);
+	READ_ONCE(other->sk_data_ready)(other);
 	sock_put(other);
 	scm_destroy(&scm);
 	return len;
@@ -2351,7 +2351,7 @@ static int queue_oob(struct sock *sk, struct msghdr *msg, struct sock *other,
 
 	sk_send_sigurg(other);
 	unix_state_unlock(other);
-	other->sk_data_ready(other);
+	READ_ONCE(other->sk_data_ready)(other);
 
 	return 0;
 out_unlock:
@@ -2477,7 +2477,7 @@ static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg,
 		spin_unlock(&other->sk_receive_queue.lock);
 
 		unix_state_unlock(other);
-		other->sk_data_ready(other);
+		READ_ONCE(other->sk_data_ready)(other);
 		sent += size;
 	}
 
-- 
2.53.0.414.gf7e9f6c205-goog

Re: [PATCH net] net: annotate data-races around sk->sk_{data_ready,write_space}

[Kuniyuki Iwashima]

On Wed, Feb 25, 2026 at 5:15 AM Eric Dumazet <edumazet@google.com> wrote:
>
> skmsg (and probably other layers) are changing these pointers
> while other cpus might read them concurrently.
>
> Add corresponding READ_ONCE()/WRITE_ONCE() annotations
> for UDP, TCP and AF_UNIX.
>
> Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
> Reported-by: syzbot+87f770387a9e5dc6b79b@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/netdev/699ee9fc.050a0220.1cd54b.0009.GAE@google.com/
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>

Re: [PATCH net] net: annotate data-races around sk->sk_{data_ready,write_space}

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 25 Feb 2026 13:15:47 +0000 you wrote:
> skmsg (and probably other layers) are changing these pointers
> while other cpus might read them concurrently.
> 
> Add corresponding READ_ONCE()/WRITE_ONCE() annotations
> for UDP, TCP and AF_UNIX.
> 
> Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
> Reported-by: syzbot+87f770387a9e5dc6b79b@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/netdev/699ee9fc.050a0220.1cd54b.0009.GAE@google.com/
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Daniel Borkmann <daniel@iogearbox.net>
> Cc: Kuniyuki Iwashima <kuniyu@google.com>
> Cc: John Fastabend <john.fastabend@gmail.com>
> Cc: Jakub Sitnicki <jakub@cloudflare.com>
> Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
> 
> [...]

Here is the summary with links:
  - [net] net: annotate data-races around sk->sk_{data_ready,write_space}
    https://git.kernel.org/netdev/net/c/2ef2b20cf4e0

You are awesome, thank you!
-- 
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