CVE-2022-27672

A flaw was found in HW. When SMT is enabled, certain AMD processors may speculatively execute instructions using a target from the sibling thread after an SMT mode switch, potentially resulting in information disclosure.

The Red Hat Enterprise Linux 8 and 9 are not affected if spectre_v2 mitigation enabled (and it is enabled by default).

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

The current mitigations for spectre V4 (or spectre_v2) should mitigate this flaw, no additional steps will need to be taken.

In more details, according to the article https://kernel.org/doc/html//next/admin-guide/hw-vuln/cross-thread-rsb.html

Two mitigations are needed:

1. Stuff the RSB during context switch which is already being done in RHEL8/RHEL9 as long as the spectre_v2 mitigation is active.
2. For KVM, the mitigation for the KVM_CAP_X86_DISABLE_EXITS capability can be turned on using the boolean module parameter mitigate_smt_rsb, e.g. vm.mitigate_smt_rsb=1.

The command to check if mitigation is active: cat /sys/devices/system/cpu/vulnerabilities/spectre_v2