CVE-2021-47389: KVM: SVM: fix missing sev_decommission in sev_receive_start

Vulnerability summary

CVE-2021-47389 is a medium (CVSS 5.1) vulnerability in linux. EPSS estimates a 0.21% chance of exploitation in the next 30 days, higher than 11.6% of scored vulnerabilities.

Timeline

1. 21-05-2024
   PublishedVulnerability first disclosed.
2. 11-05-2026
   Last modifiedVulnerability information updated.

Description

In the Linux kernel, the following vulnerability has been resolved: KVM: SVM: fix missing sev_decommission in sev_receive_start DECOMMISSION the current SEV context if binding an ASID fails after RECEIVE_START. Per AMD's SEV API, RECEIVE_START generates a new guest context and thus needs to be paired with DECOMMISSION: The RECEIVE_START command is the only command other than the LAUNCH_START command that generates a new guest context and guest handle. The missing DECOMMISSION can result in subsequent SEV launch failures, as the firmware leaks memory and might not able to allocate more SEV guest contexts in the future. Note, LAUNCH_START suffered the same bug, but was previously fixed by commit 934002cd660b ("KVM: SVM: Call SEV Guest Decommission if ASID binding fails").

• CWE-772Missing Release of Resource after Effective LifetimeThe product does not release a resource after its effective lifetime has ended, i.e., after the resource is no longer needed.