From 8952368e2aa2fda853c925c939b2a4682d054a91 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 10 Jan 2013 16:18:47 +0000 Subject: [PATCH] tcp: accept RST without ACK flag commit e566eb00dd7c2 (tcp: should drop incoming frames without ACK flag set) added a regression on the handling of RST messages. RST should be allowed to come even without ACK bit set. We validate the RST by checking the exact sequence, as requested by RFC 793 and 5961 3.2, in tcp_validate_incoming() Reported-by: Eric Wong Signed-off-by: Eric Dumazet Acked-by: Neal Cardwell Tested-by: Eric Wong Signed-off-by: David S. Miller --- net/ipv4/tcp_input.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index a28e4db8a952b..18f97ca76b002 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -5543,7 +5543,7 @@ slow_path: if (len < (th->doff << 2) || tcp_checksum_complete_user(sk, skb)) goto csum_error; - if (!th->ack) + if (!th->ack && !th->rst) goto discard; /* @@ -5988,7 +5988,7 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb, goto discard; } - if (!th->ack) + if (!th->ack && !th->rst) goto discard; if (!tcp_validate_incoming(sk, skb, th, 0)) -- 2.39.5