Commit 46462e26 authored Jul 22, 2022 by Kuniyuki Iwashima Committed by Greg Kroah-Hartman Aug 03, 2022

tcp: Fix a data-race around sysctl_tcp_comp_sack_nr.



[ Upstream commit 79f55473bfc8ac51bd6572929a679eeb4da22251 ]

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

Fixes: 9c21d2fc ("tcp: add tcp_comp_sack_nr 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 d42f68a9

net/ipv4/tcp_input.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -5303,7 +5303,7 @@ static void __tcp_ack_snd_check(struct sock *sk, int ofo_possible)
		}

		if (!tcp_is_sack(tp) \|\|
		tp->compressed_ack >= sock_net(sk)->ipv4.sysctl_tcp_comp_sack_nr)
		tp->compressed_ack >= READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_comp_sack_nr))
		goto send_now;

		if (tp->compressed_ack_rcv_nxt != tp->rcv_nxt) {