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Commit 033963b2 authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Greg Kroah-Hartman
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tcp: Fix a data-race around sysctl_tcp_mtu_probe_floor. 



[ Upstream commit 8e92d4423615a5257d0d871fc067aa561f597deb ]

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

Fixes: c04b79b6 ("tcp: add new tcp_mtu_probe_floor sysctl")
Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent fdb96b69

net/ipv4/tcp_timer.c

+1 −1
Original line number Diff line number Diff line
@@ -172,7 +172,7 @@ static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk) 
	} else {

		mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low) >> 1;

		mss = min(READ_ONCE(net->ipv4.sysctl_tcp_base_mss), mss);

		mss = max(mss, net->ipv4.sysctl_tcp_mtu_probe_floor);

		mss = max(mss, READ_ONCE(net->ipv4.sysctl_tcp_mtu_probe_floor));

		mss = max(mss, READ_ONCE(net->ipv4.sysctl_tcp_min_snd_mss));

		icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss);

	}