netdev - Re: Is it a possible bug in dev_gro

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Message-ID: <20100802110427.GA9494@gondor.apana.org.au>
Date:	Mon, 2 Aug 2010 19:04:27 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Jarek Poplawski <jarkao2@...il.com>
Cc:	Xin Xiaohui <xiaohui.xin@...el.com>, netdev@...r.kernel.org,
	davem@...emloft.net
Subject: Re: Is it a possible bug in dev_gro_receive()?

On Mon, Aug 02, 2010 at 10:29:06AM +0000, Jarek Poplawski wrote:
> Xin Xiaohui wrote:
> > I looked into the code dev_gro_receive(), found the code here:
> > if the frags[0] is pulled to 0, then the page will be released,
> > and memmove() frags left.
> > Is that right? I'm not sure if memmove do right or not, but
> > frags[0].size is never set after memove at least. what I think
> > a simple way is not to do anything if we found frags[0].size == 0.
> > The patch is as followed.
> > 
> > Or am I missing something here?
> 
> I think, you're right, but fixing memmove looks nicer to me:
> 
>  -	--skb_shinfo(skb)->nr_frags);
>  +	--skb_shinfo(skb)->nr_frags * sizeof(skb_frag_t));

I agree with the diagnosis and your proposed fix.

Thanks for catching this Xiaohui!

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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