News, via Dan Goodin, writing at Ars Technica, details a seven year old, pernicious bug in Xen virtualiztion wares. In which, users can exploit the bug to breakout of their local machines, thence into the underlying hypervisor layer. FYI - One high profile customer of the Xen Hypervisor is Amazon Web Services. Time to Patch, eh?
"Admittedly this is subtle bug, because there is no buggy code that could be spotted immediately. The bug emerges only if one looks at a bigger picture of logic flows (compare also QSB #09 for a somehow similar situation). On the other hand, it is really shocking that such a bug has been lurking in the core of the hypervisor for so many years. In our opinion the Xen project should rethink their coding guidelines and try to come up with practices and perhaps additional mechanisms that would not let similar flaws to plague the hypervisor ever again (assert-like mechanisms perhaps?). Otherwise the whole project makes no sense, at least to those who would like to use Xen for security-sensitive work." - via Dan Goodin, writing at Ars Technica.