DC402 meetup: Branch Prediction: How 20% of your CPU Became a Security Risk

We WILL be meeting at DJs this month!
This month we are IN PERSON meetup.
Join us at 6 PM for social activities (some come even earlier) and 6:30 for the main presentation.

For Apr 2025:

"Branch Prediction: How 20% of your CPU Became a Security Risk"

Modern CPUs dedicate 20% of their silicon to branch prediction as much space as the L1 cache. Why? Modern CPUs operate like an assembly line and a mispredicted branch grinds the entire factory to a halt. So to increase CPU performance, engineers created sophisticated prediction systems that try to keep the line running smoothly. But this additional complexity comes with a trade-off: there are fundamental security flaws with these techniques that remain unresolved to this day.In this talk, we'll explore how branch prediction works, why it's worth so much die space, and how this critical performance feature became one of the most significant security vulnerabilities in CPU history.

Speaker: Tim Mastny (@timmastny)
Tim Mastny is a software engineer working in data engineering and infrastructure. Outside of work, he writes about hardware, systems programming, and data science on his blog and has contributed to multiple open source projects. Previously at NASA, Boeing, and Hudl, he is now building the first modern financial infrastructure in Africa at Wave.