101–105 of 105 posts
Ouch. Before reading this article I was seriously considering deploying a signing service as a HaLVM (Haskell) Xen PV unikernel running on EC2. The service would receive its private key after startup, such that the key never touches disk. Now I'm a lot less inclined to pretend that the Xen interface actually protects me...
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In retrospect I regret bringing up the Phenom because my argument could've stood without it, and I could realistically argue either way. But my original intention was pointing out that the failure mode of the Phenom was such that it wasn't exploitable for anything other than potentially denial-of-service; it was just inconvenient, and only affected a subsystem of the CPU which worked fine without it using a firmware…
I think that is the reason for the misunderstanding.. FDIV was not really insidious in the way you describe. It was 100% predictable, certain bit patterns always gave the wrong answer in the quotient on the affected hardware and it had a very straightforward software fix (with a performance effect sure). You could demonstrate it immediately, but it really wasn't severe. (Q9 and Q10 http://www.trnicely.net/pentbug/pen…
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I too am of this opinion and am surprised this view isn't widely shared. With DDR4, we should be asking for a refund and/or starting a class-action suit, yet we're putting up with software 'mitigations' instead. I extensively test all the hardware I buy (CPU: LINPACK, RAM: MemTest86+) and if it fails any of those tests, it gets returned as "not fit for purpose". I've done this successfully a few times. A lot of other…
How do you do it, regarding LINPACK? I assume just compiling it and execute some tests that are part of it?
It is more costly, but this is a good reason to use a dedicated chunk of memory for every Xen PV domU. No oversubscription! Allowing multiple domU VMs on the same dom0 (or the equivalent in other hypervisor platforms) to re-use memory and balloon/contract memory on the fly is what enables this.
Can you point me to some services that provide, specifically, Xen PV VMs with non-oversubscribed memory? I'm considering deploying a custom unikernel for protecting the private key data for my app[1], until I have enough money for a Hardware Security Module. [1] http://security.stackexchange.com/questions/135457/penetrati...