tcp: Fix data-races around sysctl_tcp_no_ssthresh_metrics_save.
commit ab1ba21b523ab496b1a4a8e396333b24b0a18f9a upstream. While reading sysctl_tcp_no_ssthresh_metrics_save, it can be changed concurrently. Thus, we need to add READ_ONCE() to its readers. Fixes: 65e6d90168f3 ("net-tcp: Disable TCP ssthresh metrics cache by default") 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>
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@ -385,7 +385,7 @@ void tcp_update_metrics(struct sock *sk)
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if (tcp_in_initial_slowstart(tp)) {
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/* Slow start still did not finish. */
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if (!net->ipv4.sysctl_tcp_no_ssthresh_metrics_save &&
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if (!READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) &&
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!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
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val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
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if (val && (tp->snd_cwnd >> 1) > val)
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@ -401,7 +401,7 @@ void tcp_update_metrics(struct sock *sk)
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} else if (!tcp_in_slow_start(tp) &&
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icsk->icsk_ca_state == TCP_CA_Open) {
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/* Cong. avoidance phase, cwnd is reliable. */
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if (!net->ipv4.sysctl_tcp_no_ssthresh_metrics_save &&
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if (!READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) &&
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!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH))
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tcp_metric_set(tm, TCP_METRIC_SSTHRESH,
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max(tp->snd_cwnd >> 1, tp->snd_ssthresh));
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@ -418,7 +418,7 @@ void tcp_update_metrics(struct sock *sk)
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tcp_metric_set(tm, TCP_METRIC_CWND,
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(val + tp->snd_ssthresh) >> 1);
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}
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if (!net->ipv4.sysctl_tcp_no_ssthresh_metrics_save &&
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if (!READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) &&
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!tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) {
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val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
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if (val && tp->snd_ssthresh > val)
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@ -463,7 +463,7 @@ void tcp_init_metrics(struct sock *sk)
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if (tcp_metric_locked(tm, TCP_METRIC_CWND))
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tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND);
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val = net->ipv4.sysctl_tcp_no_ssthresh_metrics_save ?
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val = READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) ?
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0 : tcp_metric_get(tm, TCP_METRIC_SSTHRESH);
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if (val) {
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tp->snd_ssthresh = val;
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