This is a note to let you know that I've just added the patch titled tcp: Fix a data-race around sysctl_tcp_autocorking. to the 4.19-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_autocorking.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit b5f05fd014e0de25765497861ac2b298ad6f7e5c Author: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx> Date: Wed Jul 20 09:50:25 2022 -0700 tcp: Fix a data-race around sysctl_tcp_autocorking. [ Upstream commit 85225e6f0a76e6745bc841c9f25169c509b573d8 ] While reading sysctl_tcp_autocorking, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: f54b311142a9 ("tcp: auto corking") 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/tcp.c b/net/ipv4/tcp.c index 7acc0d07f148..768a7daab559 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -706,7 +706,7 @@ static bool tcp_should_autocork(struct sock *sk, struct sk_buff *skb, int size_goal) { return skb->len < size_goal && - sock_net(sk)->ipv4.sysctl_tcp_autocorking && + READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_autocorking) && !tcp_rtx_queue_empty(sk) && refcount_read(&sk->sk_wmem_alloc) > skb->truesize; }