SinkClose flaw impacts AMD EPYC and Ryzen CPUs, helps gain Ring -2 privileges

For those wondering what the exact attack vector is, the AMD advisory has some details:

> Improper validation in a model specific register (MSR) could allow a malicious program with ring0 access to modify SMM configuration while SMI lock is enabled, potentially leading to arbitrary code execution. [0]

[0]: https://www.amd.com/en/resources/product-security/bulletin/a...

Discussion at https://news.ycombinator.com/item?id=41204160