netdev - Re: net: Ensure partial checksum offset is inside the skb head

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Message-Id: <200906051352.02133.rusty@rustcorp.com.au>
Date:	Fri, 5 Jun 2009 13:52:01 +0930
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Herbert Xu <herbert@...dor.apana.org.au>
Cc:	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: net: Ensure partial checksum offset is inside the skb head

On Thu, 4 Jun 2009 08:52:01 pm Herbert Xu wrote:
> On Thu, Jun 04, 2009 at 09:06:00PM +1000, Herbert Xu wrote:
> > tun: Optimise handling of bogus gso->hdr_len
> >
> > As all current versions of virtio_net generate a value for the
> > header length that's too small, we should optimise this so that
> > we don't copy it twice.  This can be done by ensuring that it is
> > at least as large as the place where we'll write the checksum.
> >
> > Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
>
> With this applied we can strengthen the partial checksum check:
>
> net: Ensure partial checksum offset is inside the skb head
>
> In skb_partial_csum_set we check to see if the checksum offset
> is within the packet.  However, we really should check that it
> is within the skb head as that's the only bit we can modify
> without copying.
>
> Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>

Yep, makes sense.  FWIW:

Acked-by: Rusty Russell <rusty@...tcorp.com.au>

Thanks!
Rusty.
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