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Date: Fri, 25 Oct 2002 12:13:11 +0200
From: Alex Riesen <Alexander.Riesen@synopsys.com>
To: Florian Weimer <fw@deneb.enyo.de>
Cc: linux-kernel@vger.kernel.org, davem@redhat.com
Subject: Re: [SECURITY] CERT/CC VU#464113, SYN plus RST/FIN
Message-ID: <20021025101311.GD3512@riesen-pc.gr05.synopsys.com>
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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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