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tcp: Fix data-races around sysctl_tcp_workaround_signed_windows.

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While reading sysctl_tcp_workaround_signed_windows, it can be changed
concurrently.  Thus, we need to add READ_ONCE() to its readers.

Fixes: 15d99e02baba ("[TCP]: sysctl to allow TCP window > 32767 sans wscale")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Kuniyuki Iwashima 2022-07-20 09:50:19 -07:00 committed by David S. Miller
parent 7804764888
commit 0f1e4d0659
2 changed files with 3 additions and 3 deletions
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4
net/ipv4/tcp_output.c
View File

@ -230,7 +230,7 @@ void tcp_select_initial_window(const struct sock *sk, int __space, __u32 mss,
* which we interpret as a sign the remote TCP is not
* misinterpreting the window field as a signed quantity.
*/
if (sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows)
if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows))
(*rcv_wnd) = min(space, MAX_TCP_WINDOW);
else
(*rcv_wnd) = min_t(u32, space, U16_MAX);
@ -285,7 +285,7 @@ static u16 tcp_select_window(struct sock *sk)
* scaled window.
*/
if (!tp->rx_opt.rcv_wscale &&
sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows)
READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_workaround_signed_windows))
new_win = min(new_win, MAX_TCP_WINDOW);
else
new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale));

2
net/mptcp/options.c
View File

@ -1271,7 +1271,7 @@ raise_win:
if (unlikely(th->syn))
new_win = min(new_win, 65535U) << tp->rx_opt.rcv_wscale;
if (!tp->rx_opt.rcv_wscale &&
sock_net(ssk)->ipv4.sysctl_tcp_workaround_signed_windows)
READ_ONCE(sock_net(ssk)->ipv4.sysctl_tcp_workaround_signed_windows))
new_win = min(new_win, MAX_TCP_WINDOW);
else
new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale));