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SubjectRe: [SECURITY] CERT/CC VU#464113, SYN plus RST/FIN
On Fri, Oct 25, 2002 at 11:00:43AM +0200, Florian Weimer wrote:
> This patch prevents SYN+RST and SYN+FIN segments which arrive in the
> LISTEN state from initiating a three-way handshake.
>
> I'm not sure if it is correct, but it's better than nothing (so far, I
> haven't seen any patch for this issue).
>
> --- tcp_input.c 2002/10/25 08:45:20 1.1
> +++ tcp_input.c 2002/10/25 08:49:21
> @@ -3668,6 +3668,8 @@
> case TCP_LISTEN:
> if(th->ack)
> return 1;
> + if(th->rst || th->fin)
> + goto discard;
>
> if(th->syn) {
> if(tp->af_specific->conn_request(sk, skb) < 0)
>

You mean to place the check below "if(th->syn)", don't you?
-alex
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