From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH v5 3/7] tcp: harmonize tcp_vx_rcv header length
 assumptions
Date: Wed, 17 Feb 2010 15:47:34 -0800 (PST)
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Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
	akpm@linux-foundation.org, andi@firstfloor.org
To: william.allen.simpson@gmail.com
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From: William Allen Simpson <william.allen.simpson@gmail.com>
Date: Sun, 14 Feb 2010 01:16:28 -0500

> @@ -1559,7 +1559,8 @@ int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb)
>  		return 0;
>  	}
>  
> -	if (skb->len < tcp_hdrlen(skb) || tcp_checksum_complete(skb))
> +	/* Assumes header and options unchanged since checksum_init() */
> +	if (tcp_checksum_complete(skb))
>  		goto csum_err;
>  

Not true.

The skb->len can be modified by the call to sk_filter() done
by tcp_v4_rcv().