CVE-2021-47389 KVM: SVM: fix missing sev_decommission in sev_receive_start
Missing SEV context decommissioning in KVM SVM can cause memory leaks and prevent future SEV guest allocations, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-47389?
CVE-2021-47389 is a medium-severity denial of service vulnerability in Linux kernel, published on 21 May 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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").
Weakness: CWE-772
Which versions are affected by CVE-2021-47389?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2021-47389?
Apply the vendor's patch.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-47389 being exploited?
There is no known exploitation of CVE-2021-47389 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2021-47389, GHSA-vrx5-g53m-hhm7, UBUNTU-CVE-2021-47389.