Author here - the aim of this project was to explore exactly why such opcodes are problematic for security. Even if they're implemented with entirely innocent i

Author here - the aim of this project was to explore exactly why such opcodes are problematic for security. Even if they're implemented with entirely innocent intentions - e.g. for debug+verification purposes - they can lead to vulnerabilities in operating systems, emulators, and hypervisors. They induce edge cases which developers can't protect against if they don't know they exist in the first place (due to the lack of any public documentation). There's a more thorough writeup of the project here: https://github.com/cattius/opcodetester/blob/master/thesis.pdf https://github.com/cattius/opcodetester/blob/master/thesis.p....