[PATCH 5.18 22/88] tcp: Fix a data-race around sysctl_tcp_adv_win_scale.

Greg Kroah-Hartman
2022-08-01T12:12:22Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

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(-)

--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1437,7 +1437,7 @@ void tcp_select_initial_window(const str

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 ?