From d316488be1d9674af7dd0a8ae56f394496e42a30 Mon Sep 17 00:00:00 2001 From: Kuniyuki Iwashima Date: Mon, 18 Jul 2022 10:26:49 -0700 Subject: [PATCH] tcp: Fix a data-race around sysctl_tcp_retrans_collapse. [ Upstream commit 1a63cb91f0c2fcdeced6d6edee8d1d886583d139 ] While reading sysctl_tcp_retrans_collapse, it can be changed concurrently. Thus, we need to add READ_ONCE() to its reader. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/ipv4/tcp_output.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 5bcd12a9d8ff..3554a4c1e1b8 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -3103,7 +3103,7 @@ static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *to, struct sk_buff *skb = to, *tmp; bool first = true; - if (!sock_net(sk)->ipv4.sysctl_tcp_retrans_collapse) + if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_retrans_collapse)) return; if (TCP_SKB_CB(skb)->tcp_flags & TCPHDR_SYN) return;