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    Subject[PATCH 5.18 045/158] tcp: Fix a data-race around sysctl_tcp_mtu_probe_floor.
    Date
    From: Kuniyuki Iwashima <kuniyu@amazon.com>

    [ 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: c04b79b6cfd7 ("tcp: add new tcp_mtu_probe_floor 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>
    ---
    net/ipv4/tcp_timer.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
    index 39107bb730b0..4f3b9ab222b6 100644
    --- a/net/ipv4/tcp_timer.c
    +++ b/net/ipv4/tcp_timer.c
    @@ -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);
    }
    --
    2.35.1


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