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

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Message-Id: <20220607165005.189550617@linuxfoundation.org>
Date:   Tue,  7 Jun 2022 18:53:24 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Eric Dumazet <edumazet@...gle.com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.18 086/879] tcp: consume incoming skb leading to a reset

From: Eric Dumazet <edumazet@...gle.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@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.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