Vulnerability in AMD Processors Affecting Hypervisor Control

CVE-2022-42336

What is CVE-2022-42336?

This vulnerability involves the incorrect management of the SSBD (Speculative Store Bypass Disable) setting on AMD Family 17h and Hygon Family 18h processors. The SSBD setting requires coordination at the core level due to its shared nature among threads. The current implementation utilizes a counter to track the number of threads requiring SSBD to be active. However, there is a flaw that can lead to underflow or overflow of this counter during guest operations, potentially causing the saturation of the SSBD state. This results in the hypervisor incorrectly assessing the SSBD state for threads on the same core, leaving those threads without the intended protection, which could be exploited by malicious actors.

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