DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=gamma;
        h=date:from:to:cc:subject:message-id:references:mime-version
         :content-type:content-disposition:in-reply-to:user-agent;
        b=oNT1CtYOGwLkP4NHUZ9EPJ3E386kEgr9KpWwr40Chq3jVKMJQgUCDQg5pi2RE0OgWs
         3qhQdKJHg7Wq7HsgYJ1esk6Bom3O4UPZeAj2l7qMpBgFRD2Pn1T3aGKiA41VfkYaKFkl
         pFpQW3Zdcffal7sjwIbRaUtOybdWta65seW24=
Date: Tue, 27 Jan 2009 10:35:11 +0000
From: Jarek Poplawski <jarkao2@gmail.com>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: David Miller <davem@davemloft.net>, zbr@ioremap.net, w@1wt.eu,
       dada1@cosmosbay.com, ben@zeus.com, mingo@elte.hu,
       linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
       jens.axboe@oracle.com
Subject: Re: [PATCH v3] tcp: splice as many packets as possible at once
Message-ID: <20090127103511.GE4197@ff.dom.local>
References: <20090125.212203.15909648.davem@davemloft.net> <20090127071130.GA29125@gondor.apana.org.au> <20090127075418.GB4197@ff.dom.local> <20090127100958.GA30239@gondor.apana.org.au>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20090127100958.GA30239@gondor.apana.org.au>
User-Agent: Mutt/1.5.18 (2008-05-17)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1069
Lines: 24

On Tue, Jan 27, 2009 at 09:09:58PM +1100, Herbert Xu wrote:
> On Tue, Jan 27, 2009 at 07:54:18AM +0000, Jarek Poplawski wrote:
> > 
> > Yes, but ip_append_data() (and skb_append_datato_frags() for
> > NETIF_F_UFO only, so currently not a problem), uses this differently,
> > and these pages in sk->sk_sndmsg_page could leak or be used after
> > kfree. (I didn't track locking in these other places).
> 
> It'll be freed when the socket is freed so that should be fine.
> 

I don't think so: these places can overwrite sk->sk_sndmsg_page left
after tcp_sendmsg(), or skb_splice_bits() now, with NULL or a new
pointer without put_page() (they only reference copied chunks and
expect auto freeing). On the other hand, if tcp_sendmsg() reads after
them it could use a pointer after the page is freed, I guess.

Cheers,
Jarek P.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/