From 7b514a886ba50e3b99295b00805f0d5ad750ca66 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 c3ae62af8e755 (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 a28e4db..18f97ca 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)) -- 2.7.4