I read the article and I really liked that the author tried to make it seem as simple as possible that you don't need a degree or a deep understanding of how CPUs work to understand the issue.
However, one thing that bothers me is that the author claims it's possible to retrieve private keys or root passwords by triggering a faulty revert from the instruction that resets the upper bits of a register. Where is the demo results? All I see is a small-enough gif that looks like the Matrix terminal text scrolling through. Is there any way (other than running the exploit program myself) to check the results and see that it actually leaked the root password and other information?
The exploit will leak more or less random data (data which was accessed recently by the CPU). You cannot target a specific part of the memory, but you can keep fetching data until you get something interesting.
so if I wanted to test if it leaks my root password, I should run the code and open a terminal and say, upgrade packages, or upgrade packages before running the exploit code?
The only way would be to let the thing run and say, pipe the output to grep looking for your password or something else you're looking for. SIMD instructions are used very often for parsing text so I wouldn't be surprised if sensitive passwords eventually get loaded into an YMM register and the exploit just so happened to dump that.
However, one thing that bothers me is that the author claims it's possible to retrieve private keys or root passwords by triggering a faulty revert from the instruction that resets the upper bits of a register. Where is the demo results? All I see is a small-enough gif that looks like the Matrix terminal text scrolling through. Is there any way (other than running the exploit program myself) to check the results and see that it actually leaked the root password and other information?