From afc324c769decfa27cc37f1715e2e94bbe2a1b27 Mon Sep 17 00:00:00 2001
From: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Wed, 7 Sep 2022 09:24:16 +0000
Subject: [PATCH] tcp: Fix a data-race around sysctl_tcp_thin_linear_timeouts.
stable inclusion
from stable-v4.19.254
commit f4b0295be9a3c4260de4585fac4062e602a88ac7
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5Q0SQ
CVE: NA
--------------------------------
[ Upstream commit 7c6f2a86ca590d5187a073d987e9599985fb1c7c ]
While reading sysctl_tcp_thin_linear_timeouts, it can be changed
concurrently. Thus, we need to add READ_ONCE() to its reader.
Fixes: 36e31b0af587 ("net: TCP thin linear timeouts")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>
---
net/ipv4/tcp_timer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index e905fff09fea..84069db0423a 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -545,7 +545,7 @@ void tcp_retransmit_timer(struct sock *sk)
* linear-timeout retransmissions into a black hole
*/
if (sk->sk_state == TCP_ESTABLISHED &&
- (tp->thin_lto || net->ipv4.sysctl_tcp_thin_linear_timeouts) &&
+ (tp->thin_lto || READ_ONCE(net->ipv4.sysctl_tcp_thin_linear_timeouts)) &&
tcp_stream_is_thin(tp) &&
icsk->icsk_retransmits <= TCP_THIN_LINEAR_RETRIES) {
icsk->icsk_backoff = 0;
--
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