Commit 492f3713 authored Jul 18, 2022 by Kuniyuki Iwashima Committed by Greg Kroah-Hartman Jul 29, 2022

tcp: Fix a data-race around sysctl_tcp_thin_linear_timeouts.



[ Upstream commit 7c6f2a86ca590d5187a073d987e9599985fb1c7c ]

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

Fixes: 36e31b0a ("net: TCP thin linear timeouts")
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 92c35113

net/ipv4/tcp_timer.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -569,7 +569,7 @@ void tcp_retransmit_timer(struct sock *sk)
		* linear-timeout retransmissions into a black hole
		*/
		if (sk->sk_state == TCP_ESTABLISHED &&
		(tp->thin_lto \|\| net->ipv4.sysctl_tcp_thin_linear_timeouts) &&
		(tp->thin_lto \|\| READ_ONCE(net->ipv4.sysctl_tcp_thin_linear_timeouts)) &&
		tcp_stream_is_thin(tp) &&
		icsk->icsk_retransmits <= TCP_THIN_LINEAR_RETRIES) {
		icsk->icsk_backoff = 0;