netdev - Re: [PATCH 6/6] xen-netback: don't disconnect frontend when seeing oversize frame

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Message-ID: <20130325120007.GA21271@zion.uk.xensource.com>
Date:	Mon, 25 Mar 2013 12:00:07 +0000
From:	Wei Liu <wei.liu2@...rix.com>
To:	David Vrabel <david.vrabel@...rix.com>
CC:	"xen-devel@...ts.xen.org" <xen-devel@...ts.xen.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Ian Campbell <Ian.Campbell@...rix.com>,
	"annie.li@...cle.com" <annie.li@...cle.com>,
	"konrad.wilk@...cle.com" <konrad.wilk@...cle.com>
Subject: Re: [PATCH 6/6] xen-netback: don't disconnect frontend when seeing
 oversize frame

On Mon, Mar 25, 2013 at 11:47:17AM +0000, David Vrabel wrote:
> On 25/03/13 11:08, Wei Liu wrote:
> > Some buggy frontends may generate frames larger than 64 KiB. We should
> > aggresively consume all slots and drop the packet instead of disconnecting the
> > frontend.
> 
> The following is the changeset description I wrote internally.  It's a
> bit more descriptive.
> 
> Apologies for not sending out a proper patch in the first place.
> 
> "Some frontend drivers are sending packets >= 64 KiB in length.  This
> length overflows the length field in the first frag making the
> following frags have an invalid length ("Frag is bigger than frame").
> 
> Turn this error back into a non-fatal error by dropping the packet.
> To avoid having the following frags having fatal errors, consume all
> frags in the packet.
> 
> This does not reopen the security hole as if the packet as an invalid
> number of frags it will still hit this fatal error case."
> 

Thanks.

Overall this looks good. I will need to change 'frags' to 'slots'
though.


Wei.

> David
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