CVE-2025-22013 KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state
A flaw in Linux KVM arm64 allows host FPSIMD/SVE state leakage or corruption, potentially exposing sensitive data or causing crashes.
- 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-2025-22013?
CVE-2025-22013 is a high-severity vulnerability in Linux kernel, published on 8 Apr 2025. 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: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state
There are several problems with the way hyp code lazily saves the host's FPSIMD/SVE state, including:
* Host SVE being discarded unexpectedly due to inconsistent configuration of TIF_SVE and CPACR_ELx.ZEN. This has been seen to result in QEMU crashes where SVE is used by memmove(), as reported by Eric Auger:
https://issues.redhat.com/browse/RHEL-68997
* Host SVE state is discarded *after* modification by ptrace, which was an unintentional ptrace ABI change introduced with lazy discarding of SVE state.
* The host FPMR value can be discarded when running a non-protected VM, where FPMR support is not exposed to a VM, and that VM uses FPSIMD/SVE. In these cases the hyp code does not save the host's FPMR before unbinding the host's FPSIMD/SVE/SME state, leaving a stale value in memory.
Avoid these by eagerly saving and "flushing" the host's FPSIMD/SVE/SME state when loading a vCPU such that KVM does not need to save any of the host's FPSIMD/SVE/SME state. For clarity, fpsimd_kvm_prepare() is removed and the necessary call to fpsimd_save_and_flush_cpu_state() is placed in kvm_arch_vcpu_load_fp(). As 'fpsimd_state' and 'fpmr_ptr' should not be used, they are set to NULL; all uses of these will be removed in subsequent patches.
Historical problems go back at least as far as v5.17, e.g. erroneous assumptions about TIF_SVE being clear in commit:
8383741ab2e773a9 ("KVM: arm64: Get rid of host SVE tracking/saving")
... and so this eager save+flush probably needs to be backported to ALL stable trees.
Which versions are affected by CVE-2025-22013?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2025-22013?
Apply the vendor's patch.
Is CVE-2025-22013 being exploited?
There is no known exploitation of CVE-2025-22013 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2025-22013, DEBIAN-CVE-2025-22013, GHSA-7jf9-69m7-87p6, ROOT-OS-UBUNTU-2404-CVE-2025-22013, UBUNTU-CVE-2025-22013.