This is a note to let you know that I've just added the patch titled
tcp: annotate lockless access to sk->sk_err
to the 6.1-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:
tcp-annotate-lockless-access-to-sk-sk_err.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 465413ac31f0593d6aeeb26a69d666e824901ce5
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date: Wed Mar 15 20:57:44 2023 +0000
tcp: annotate lockless access to sk->sk_err
[ Upstream commit e13ec3da05d130f0d10da8e1fbe1be26dcdb0e27 ]
tcp_poll() reads sk->sk_err without socket lock held/owned.
We should used READ_ONCE() here, and update writers
to use WRITE_ONCE().
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Stable-dep-of: 853c3bd7b791 ("tcp: fix race in tcp_write_err()")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 2d4f697d338f5..7e162a34baec2 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -591,7 +591,8 @@ __poll_t tcp_poll(struct file *file, struct socket *sock, poll_table *wait)
}
/* This barrier is coupled with smp_wmb() in tcp_reset() */
smp_rmb();
- if (sk->sk_err || !skb_queue_empty_lockless(&sk->sk_error_queue))
+ if (READ_ONCE(sk->sk_err) ||
+ !skb_queue_empty_lockless(&sk->sk_error_queue))
mask |= EPOLLERR;
return mask;
@@ -3119,7 +3120,7 @@ int tcp_disconnect(struct sock *sk, int flags)
if (old_state == TCP_LISTEN) {
inet_csk_listen_stop(sk);
} else if (unlikely(tp->repair)) {
- sk->sk_err = ECONNABORTED;
+ WRITE_ONCE(sk->sk_err, ECONNABORTED);
} else if (tcp_need_reset(old_state) ||
(tp->snd_nxt != tp->write_seq &&
(1 << old_state) & (TCPF_CLOSING | TCPF_LAST_ACK))) {
@@ -3127,9 +3128,9 @@ int tcp_disconnect(struct sock *sk, int flags)
* states
*/
tcp_send_active_reset(sk, gfp_any());
- sk->sk_err = ECONNRESET;
+ WRITE_ONCE(sk->sk_err, ECONNRESET);
} else if (old_state == TCP_SYN_SENT)
- sk->sk_err = ECONNRESET;
+ WRITE_ONCE(sk->sk_err, ECONNRESET);
tcp_clear_xmit_timers(sk);
__skb_queue_purge(&sk->sk_receive_queue);
@@ -4735,7 +4736,7 @@ int tcp_abort(struct sock *sk, int err)
bh_lock_sock(sk);
if (!sock_flag(sk, SOCK_DEAD)) {
- sk->sk_err = err;
+ WRITE_ONCE(sk->sk_err, err);
/* This barrier is coupled with smp_rmb() in tcp_poll() */
smp_wmb();
sk_error_report(sk);
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index fa15c6951cd78..d72255e5262b3 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4370,15 +4370,15 @@ void tcp_reset(struct sock *sk, struct sk_buff *skb)
/* We want the right error as BSD sees it (and indeed as we do). */
switch (sk->sk_state) {
case TCP_SYN_SENT:
- sk->sk_err = ECONNREFUSED;
+ WRITE_ONCE(sk->sk_err, ECONNREFUSED);
break;
case TCP_CLOSE_WAIT:
- sk->sk_err = EPIPE;
+ WRITE_ONCE(sk->sk_err, EPIPE);
break;
case TCP_CLOSE:
return;
default:
- sk->sk_err = ECONNRESET;
+ WRITE_ONCE(sk->sk_err, ECONNRESET);
}
/* This barrier is coupled with smp_rmb() in tcp_poll() */
smp_wmb();
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 8fbb6deed3216..16098fcafde2b 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -603,7 +603,7 @@ int tcp_v4_err(struct sk_buff *skb, u32 info)
ip_icmp_error(sk, skb, err, th->dest, info, (u8 *)th);
if (!sock_owned_by_user(sk)) {
- sk->sk_err = err;
+ WRITE_ONCE(sk->sk_err, err);
sk_error_report(sk);
@@ -632,7 +632,7 @@ int tcp_v4_err(struct sk_buff *skb, u32 info)
inet = inet_sk(sk);
if (!sock_owned_by_user(sk) && inet->recverr) {
- sk->sk_err = err;
+ WRITE_ONCE(sk->sk_err, err);
sk_error_report(sk);
} else { /* Only an error on timeout */
WRITE_ONCE(sk->sk_err_soft, err);
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 15f814c1e1693..19b5a6179c061 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -3764,7 +3764,7 @@ static void tcp_connect_init(struct sock *sk)
tp->rx_opt.rcv_wscale = rcv_wscale;
tp->rcv_ssthresh = tp->rcv_wnd;
- sk->sk_err = 0;
+ WRITE_ONCE(sk->sk_err, 0);
sock_reset_flag(sk, SOCK_DONE);
tp->snd_wnd = 0;
tcp_init_wl(tp, 0);
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index fe23a427f6a9d..117fc7031bc10 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -67,7 +67,7 @@ u32 tcp_clamp_probe0_to_user_timeout(const struct sock *sk, u32 when)
static void tcp_write_err(struct sock *sk)
{
- sk->sk_err = READ_ONCE(sk->sk_err_soft) ? : ETIMEDOUT;
+ WRITE_ONCE(sk->sk_err, READ_ONCE(sk->sk_err_soft) ? : ETIMEDOUT);
sk_error_report(sk);
tcp_write_queue_purge(sk);
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 848175e0be081..35bfca93af6ad 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -493,7 +493,7 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
ipv6_icmp_error(sk, skb, err, th->dest, ntohl(info), (u8 *)th);
if (!sock_owned_by_user(sk)) {
- sk->sk_err = err;
+ WRITE_ONCE(sk->sk_err, err);
sk_error_report(sk); /* Wake people up to see the error (see connect in sock.c) */
tcp_done(sk);
@@ -513,7 +513,7 @@ static int tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
}
if (!sock_owned_by_user(sk) && np->recverr) {
- sk->sk_err = err;
+ WRITE_ONCE(sk->sk_err, err);
sk_error_report(sk);
} else {
WRITE_ONCE(sk->sk_err_soft, err);
