This is a note to let you know that I've just added the patch titled
tcp: Fix a data-race around sysctl_tcp_ecn_fallback.
to the 5.18-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-fix-a-data-race-around-sysctl_tcp_ecn_fallback.patch
and it can be found in the queue-5.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 1c28c67b1b9a6964e6f27e8193a8cc61081ae2c7
Author: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Date: Mon Jul 11 17:15:31 2022 -0700
tcp: Fix a data-race around sysctl_tcp_ecn_fallback.
[ Upstream commit 12b8d9ca7e678abc48195294494f1815b555d658 ]
While reading sysctl_tcp_ecn_fallback, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its reader.
Fixes: 492135557dc0 ("tcp: add rfc3168, section 6.1.1.1. fallback")
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 11add5214713..ffe0264a51b8 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -689,6 +689,8 @@ static struct ctl_table ipv4_net_table[] = {
.maxlen = sizeof(u8),
.mode = 0644,
.proc_handler = proc_dou8vec_minmax,
+ .extra1 = SYSCTL_ZERO,
+ .extra2 = SYSCTL_ONE,
},
{
.procname = "ip_dynaddr",
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 9eefe7f6370f..34249469e361 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -346,7 +346,7 @@ static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb)
static void tcp_ecn_clear_syn(struct sock *sk, struct sk_buff *skb)
{
- if (sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback)
+ if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_ecn_fallback))
/* tp->ecn_flags are cleared at a later point in time when
* SYN ACK is ultimatively being received.
*/
