Re: [Xen-devel] workaround for dom0 crash due to QEMU using O_DIRECT

[Alex Bligh <alex@xxxxxxxxxxx>]

Ian,

--On 8 July 2013 21:48:17 +0100 Ian Campbell <ian.campbell@xxxxxxxxxx> 
wrote:
> > Have we not got a danger here that trade_page could end up written
> > to with VM A's data, and this could then find itself in VM B's disk?
> > Or do we know that every access by the kernel after withdrawal
> > of the grant is guaranteed to be a read? In which case making it read
> > only might be safer.
> It absolutely should be read only. AFAICT that means PAGE_KERNEL_RO
> rather than the PAGE_KERNEL in the patch.
OK. We should test with that then (Diana: NB)

> The case we are worried about is read-after-free on the network tx path.
> There can be no write-after-free on the network rx path.
Yes I couldn't think of a realistic scenario where this would happen,
but something just feels wrong about the page not being read-only.

--
Alex Bligh

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