From: Kuniyuki Iwashima Date: Mon, 18 Jul 2022 17:26:48 +0000 (-0700) Subject: tcp: Fix data-races around sysctl_tcp_slow_start_after_idle. X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=41aeba4506f6b70ec7500c6fe202731a4ba29fe5;p=linux.git tcp: Fix data-races around sysctl_tcp_slow_start_after_idle. [ Upstream commit 4845b5713ab18a1bb6e31d1fbb4d600240b8b691 ] While reading sysctl_tcp_slow_start_after_idle, it can be changed concurrently. Thus, we need to add READ_ONCE() to its readers. Fixes: 35089bb203f4 ("[TCP]: Add tcp_slow_start_after_idle sysctl.") Signed-off-by: Kuniyuki Iwashima Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- diff --git a/include/net/tcp.h b/include/net/tcp.h index 0c609d10c3204..8ce8aafeef0f5 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1390,8 +1390,8 @@ static inline void tcp_slow_start_after_idle_check(struct sock *sk) struct tcp_sock *tp = tcp_sk(sk); s32 delta; - if (!sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle || tp->packets_out || - ca_ops->cong_control) + if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle) || + tp->packets_out || ca_ops->cong_control) return; delta = tcp_jiffies32 - tp->lsndtime; if (delta > inet_csk(sk)->icsk_rto) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 3b71d87359954..94f7841f7bfb1 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1901,7 +1901,7 @@ static void tcp_cwnd_validate(struct sock *sk, bool is_cwnd_limited) if (tp->packets_out > tp->snd_cwnd_used) tp->snd_cwnd_used = tp->packets_out; - if (sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle && + if (READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle) && (s32)(tcp_jiffies32 - tp->snd_cwnd_stamp) >= inet_csk(sk)->icsk_rto && !ca_ops->cong_control) tcp_cwnd_application_limited(sk);