From 3be498bcf6ea671debc4f6ebe03f8560fadc9cac Mon Sep 17 00:00:00 2001
From: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Wed, 20 Jul 2022 09:50:14 -0700
Subject: [PATCH] tcp: Fix a data-race around sysctl_tcp_adv_win_scale.
commit 36eeee75ef0157e42fb6593dcc65daab289b559e upstream.
While reading sysctl_tcp_adv_win_scale, 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 <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/net/tcp.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index aaf1d5d5a13b0..8459145497b74 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1389,7 +1389,7 @@ void tcp_select_initial_window(const struct sock *sk, int __space,
static inline int tcp_win_from_space(const struct sock *sk, int space)
{
- int tcp_adv_win_scale = sock_net(sk)->ipv4.sysctl_tcp_adv_win_scale;
+ int tcp_adv_win_scale = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_adv_win_scale);
return tcp_adv_win_scale <= 0 ?
(space>>(-tcp_adv_win_scale)) :
--
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