netdev - Re: [PATCH 1/2] virtio-net: Verify page list size before fitting into skb

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Message-ID: <1317067055.20885.5.camel@lappy>
Date:	Mon, 26 Sep 2011 22:57:35 +0300
From:	Sasha Levin <levinsasha928@...il.com>
To:	Pekka Enberg <penberg@...helsinki.fi>
Cc:	"Michael S. Tsirkin" <mst@...hat.com>,
	linux-kernel@...r.kernel.org,
	Rusty Russell <rusty@...tcorp.com.au>,
	virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
	kvm@...r.kernel.org
Subject: Re: [PATCH 1/2] virtio-net: Verify page list size before fitting
 into skb

On Mon, 2011-09-26 at 22:45 +0300, Pekka Enberg wrote:
> On Mon, Sep 26, 2011 at 10:37 PM, Sasha Levin <levinsasha928@...il.com> wrote:
> >> Interesting.  This is a theoretical issue, correct?
> >> Not a crash you actually see.
> >
> > Actually it was an actual crash caused when our virtio-net driver in kvm
> > tools did funny things and passed '(u32)-1' length as a buffer length to
> > the guest kernel.
> 
> I'm not sure what Michael means with "theoretical issue" here. Can the guest
> driver assume that the hypervisor doesn't attempt to do nasty things?

afaik if the hypervisor can access the vcpus and the memory of the
guest, this shouldn't be a security issue - more of a bug prevention
issue.

I guess it'll be interesting the other way around, when it's the guest
that passes this buggy information to the hypervisor.

-- 

Sasha.

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