Again? on April 4, 2021, 10:58 28 comments
In brief: AMD has confirmed that a microarchitecture optimization inside Zen 3 CPUs can be exploited in a similar fashion to the Spectre vulnerabilities that plagued Intel CPUs a few generations ago. Disabling the optimization is possible, but will carry a performance penalty that AMD doesn’t believe is worth it for all but the most critical deployments of the processors.
In a recently published whitepaper, titled Security Analysis of AMD Predictive Store Forwarding, AMD describes the nature of the vulnerability and discusses the associated complications. In simple terms, the implementation of Predictive Store Forwarding (PSF) reopens the lines of attack previously threatened by Spectre v1, v2, and v4, because of its speculative nature.