[PATCH 5.18 086/879] tcp: consume incoming skb leading to a reset

Greg Kroah-Hartman
2022-06-07T22:06:52Z

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 60f99e9fb6d1..1f3ce7aea716 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5711,7 +5711,7 @@ 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;
}
@@ -5747,17 +5747,16 @@ 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;
}

@@ -5782,6 +5781,11 @@ 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