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    Subject[PATCH 5.17 078/772] tcp: consume incoming skb leading to a reset
    Date
    From: Eric Dumazet <edumazet@google.com>

    [ Upstream commit d9d024f96609016628d750ebc8ee4a6f0d80e6e1 ]

    Whenever tcp_validate_incoming() handles a valid RST packet,
    we should not pretend the packet was dropped.

    Create a special section at the end of tcp_validate_incoming()
    to handle this case.

    Signed-off-by: Eric Dumazet <edumazet@google.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    net/ipv4/tcp_input.c | 28 ++++++++++++++++------------
    1 file changed, 16 insertions(+), 12 deletions(-)

    diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
    index 7bf84ce34d9e..96c25c97ee56 100644
    --- a/net/ipv4/tcp_input.c
    +++ b/net/ipv4/tcp_input.c
    @@ -5694,7 +5694,7 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
    &tp->last_oow_ack_time))
    tcp_send_dupack(sk, skb);
    } else if (tcp_reset_check(sk, skb)) {
    - tcp_reset(sk, skb);
    + goto reset;
    }
    goto discard;
    }
    @@ -5730,17 +5730,16 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
    }

    if (rst_seq_match)
    - tcp_reset(sk, skb);
    - else {
    - /* Disable TFO if RST is out-of-order
    - * and no data has been received
    - * for current active TFO socket
    - */
    - if (tp->syn_fastopen && !tp->data_segs_in &&
    - sk->sk_state == TCP_ESTABLISHED)
    - tcp_fastopen_active_disable(sk);
    - tcp_send_challenge_ack(sk);
    - }
    + goto reset;
    +
    + /* Disable TFO if RST is out-of-order
    + * and no data has been received
    + * for current active TFO socket
    + */
    + if (tp->syn_fastopen && !tp->data_segs_in &&
    + sk->sk_state == TCP_ESTABLISHED)
    + tcp_fastopen_active_disable(sk);
    + tcp_send_challenge_ack(sk);
    goto discard;
    }

    @@ -5765,6 +5764,11 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
    discard:
    tcp_drop(sk, skb);
    return false;
    +
    +reset:
    + tcp_reset(sk, skb);
    + __kfree_skb(skb);
    + return false;
    }

    /*
    --
    2.35.1


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