Domas: Bypassing memory protection with AMD's memory controllers

Christopher Domas has published a proof of concept with a description showing how to use AMD memory controllers' bank swizzle mode to bypass memory protection and read or write arbitrary data, including CPU microcode definitions and memory belonging to the platform security processor. Among other things, this allows code running at the kernel level to directly manipulate the meaning of processor instructions, potentially bypassing other security measures such as memory encryption and virtual machine isolation. This is not, strictly, unexpected behavior: it is documented in AMD's manual (on page 113 of that PDF). But the fact that it can be used to access arbitrary memory and thereby rewrite supposedly immutable parts of the...

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