netdev - Re: [PATCH net] tcp: fix req->saved

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Message-ID: <1446755819.4184.52.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Thu, 05 Nov 2015 12:36:59 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev <netdev@...r.kernel.org>, Ying Cai <ycai@...gle.com>
Subject: Re: [PATCH net] tcp: fix req->saved_syn race

On Thu, 2015-11-05 at 11:07 -0800, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
> 
> For the reasons explained in commit ce1050089c96 ("tcp/dccp: fix
> ireq->pktopts race"), we need to make sure we do not access
> req->saved_syn unless we own the request sock.
> 
> This fixes races for listeners using TCP_SAVE_SYN option.

>  	*own_req = inet_ehash_nolisten(newsk, req_to_sk(req_unhash));


> +	if (*own_req)
> +		tcp_move_syn(newtp, req_unhash);
>  
>  	return newsk;

Humpff, req_unhash needs to be 'req', otherwise we will crash for FAST
OPEN connections (for which req_unhash == NULL)

I will send a fix, sorry for this David :(



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