Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 369d99c2 authored Jul 18, 2022 by Kuniyuki Iwashima Committed by Greg Kroah-Hartman Jul 29, 2022

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: 35089bb2 ("[TCP]: Add tcp_slow_start_after_idle sysctl.")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 492f3713

include/net/tcp.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -1373,8 +1373,8 @@ 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)

net/ipv4/tcp_output.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1673,7 +1673,7 @@ 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);