CVE-2024-26990 KVM: x86/mmu: Write-protect L2 SPTEs in TDP MMU when clearing dirty status
A flaw in Linux KVM TDP MMU allows L2 guests to bypass dirty logging, potentially leaking memory state to the host or other guests.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-26990?
CVE-2024-26990 is a high-severity vulnerability in Linux kernel, published on 1 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: x86/mmu: Write-protect L2 SPTEs in TDP MMU when clearing dirty status
Check kvm_mmu_page_ad_need_write_protect() when deciding whether to write-protect or clear D-bits on TDP MMU SPTEs, so that the TDP MMU accounts for any role-specific reasons for disabling D-bit dirty logging.
Specifically, TDP MMU SPTEs must be write-protected when the TDP MMU is being used to run an L2 (i.e. L1 has disabled EPT) and PML is enabled. KVM always disables PML when running L2, even when L1 and L2 GPAs are in the some domain, so failing to write-protect TDP MMU SPTEs will cause writes made by L2 to not be reflected in the dirty log.
[sean: massage shortlog and changelog, tweak ternary op formatting]
Which versions are affected by CVE-2024-26990?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-26990?
Apply the vendor's patch.
Is CVE-2024-26990 being exploited?
There is no known exploitation of CVE-2024-26990 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-26990, DEBIAN-CVE-2024-26990, GHSA-q5p9-3w3f-hr85, UBUNTU-CVE-2024-26990.