From: Kuniyuki Iwashima Date: Wed, 20 Jul 2022 16:50:17 +0000 (-0700) Subject: tcp: Fix data-races around sysctl_tcp_no_ssthresh_metrics_save. X-Git-Tag: v5.15.73~1886 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=62e721dee8ccf70c7652c8424f6f9fa5874c924d;p=platform%2Fkernel%2Flinux-rpi.git 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 Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- diff --git a/net/ipv4/tcp_metrics.c b/net/ipv4/tcp_metrics.c index 9dcc418..d58e672 100644 --- a/net/ipv4/tcp_metrics.c +++ b/net/ipv4/tcp_metrics.c @@ -385,7 +385,7 @@ void tcp_update_metrics(struct sock *sk) if (tcp_in_initial_slowstart(tp)) { /* Slow start still did not finish. */ - if (!net->ipv4.sysctl_tcp_no_ssthresh_metrics_save && + if (!READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) && !tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) { val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH); if (val && (tcp_snd_cwnd(tp) >> 1) > val) @@ -401,7 +401,7 @@ void tcp_update_metrics(struct sock *sk) } else if (!tcp_in_slow_start(tp) && icsk->icsk_ca_state == TCP_CA_Open) { /* Cong. avoidance phase, cwnd is reliable. */ - if (!net->ipv4.sysctl_tcp_no_ssthresh_metrics_save && + if (!READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) && !tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) tcp_metric_set(tm, TCP_METRIC_SSTHRESH, max(tcp_snd_cwnd(tp) >> 1, tp->snd_ssthresh)); @@ -418,7 +418,7 @@ void tcp_update_metrics(struct sock *sk) tcp_metric_set(tm, TCP_METRIC_CWND, (val + tp->snd_ssthresh) >> 1); } - if (!net->ipv4.sysctl_tcp_no_ssthresh_metrics_save && + if (!READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) && !tcp_metric_locked(tm, TCP_METRIC_SSTHRESH)) { val = tcp_metric_get(tm, TCP_METRIC_SSTHRESH); if (val && tp->snd_ssthresh > val) @@ -463,7 +463,7 @@ void tcp_init_metrics(struct sock *sk) if (tcp_metric_locked(tm, TCP_METRIC_CWND)) tp->snd_cwnd_clamp = tcp_metric_get(tm, TCP_METRIC_CWND); - val = net->ipv4.sysctl_tcp_no_ssthresh_metrics_save ? + val = READ_ONCE(net->ipv4.sysctl_tcp_no_ssthresh_metrics_save) ? 0 : tcp_metric_get(tm, TCP_METRIC_SSTHRESH); if (val) { tp->snd_ssthresh = val;