I worked on mitigating CPU ‘Meltdown’ bug, 5 years before it was known about

Maybe a clickbait title, sorry, but I couldn’t think of a better title.

The CPU ‘Meltdown’ bug affects Intel CPUs, and from Wikipedia:

Since many operating systems map physical memory, kernel processes, and other running user space processes into the address space of every process, Meltdown effectively makes it possible for a rogue process to read any physical, kernel or other processes’ mapped memory—regardless of whether it should be able to do so. Defenses against Meltdown would require avoiding the use of memory mapping in a manner vulnerable to such exploits (i.e. a software-based solution) or avoidance of the underlying race condition (i.e. a modification to the CPUs’ microcode and/or execution path).

This separation of user and kernel memory space is exactly what I worked on from 2012 to 2014 on behalf on Deutsch Telekom using the L4 hypervisor:


The idea was to give each service its own separate memory space, designing in a way such that you assume that the main OS has been compromised and is not trustworthy (e.g. because of the Meltdown bug). I personally worked on the graphics driver – splitting the kernel graphics driver into two parts – one side for the app to talk to and has to be considered compromised, and one side that actually talks to the hardware.

Here’s my work in action:




Yes, I did actually use Angry Birds as my test. Fully hardware accelerated too 🙂

Unfortunately the problem was that it took too long to port each phone across.  It took me a year to port across graphics driver changes, and a similar time for my colleagues to do the other drivers.  And then another year for it to actually hit the market.  The result is that the phone was always over 2 years out of date by the time it hit the market, which is a long time in mobile phone times.

Still, our software would be immune to this type of bug, and that’s kinda cool.  Even if it did fail commercially 😉


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