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    Subject[PATCH 5.18 48/88] tcp: Fix a data-race around sysctl_tcp_min_rtt_wlen.
    Date
    From: Kuniyuki Iwashima <kuniyu@amazon.com>

    [ Upstream commit 1330ffacd05fc9ac4159d19286ce119e22450ed2 ]

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

    Fixes: f672258391b4 ("tcp: track min RTT using windowed min-filter")
    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_input.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
    index 78e16891f12b..f3b658fa3e7b 100644
    --- a/net/ipv4/tcp_input.c
    +++ b/net/ipv4/tcp_input.c
    @@ -3058,7 +3058,7 @@ static void tcp_fastretrans_alert(struct sock *sk, const u32 prior_snd_una,

    static void tcp_update_rtt_min(struct sock *sk, u32 rtt_us, const int flag)
    {
    - u32 wlen = sock_net(sk)->ipv4.sysctl_tcp_min_rtt_wlen * HZ;
    + u32 wlen = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_min_rtt_wlen) * HZ;
    struct tcp_sock *tp = tcp_sk(sk);

    if ((flag & FLAG_ACK_MAYBE_DELAYED) && rtt_us > tcp_min_rtt(tp)) {
    --
    2.35.1


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