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Re: [Xen-devel] [PATCH] xenstored: allow guests to reintroduce themselves

On 08/09/2011 11:14 AM, Keir Fraser wrote:
On 09/08/2011 11:08, "Vincent Hanquez"<vincent.hanquez@xxxxxxxxxxxxx>

xenstored: allow guests to reintroduce themselves

During kexec all old watches have to be removed, otherwise the new
kernel will receive unexpected events. Allow a guest to introduce itself
and cleanup all of its watches.

What about security wise ?

Guest userspace suddenly becomes able to do this operation (and DoS themself)
where they used to be limited to normal read/write/.. operations.

Guest userspace can already DoS the guest if it has access to xenstore, by
messing with xenbus I/O connections, for example.

How so ?
It seems we validate userspace packets (at least on linux) before actually 
putting them on the ring.


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