cbcvebase.
CVE-2025-22013
published 2025-04-08

CVE-2025-22013: In the Linux kernel, the following vulnerability has been resolved: KVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state There are several problems…

PriorityP421medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.20%
9.7th percentile
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.

Affected

16 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.12.21-1 (forky)linux 6.12.21-1 (forky)
linuxlinux
linuxlinux>= 93ae6b01bafee8fa385aa25ee7ebdb40057f6abe < 806d5c1e1d2e5502175a24bf70f251648d99c36a806d5c1e1d2e5502175a24bf70f251648d99c36a
linuxlinux>= 93ae6b01bafee8fa385aa25ee7ebdb40057f6abe < 79e140bba70bcacc5fe15bf8c0b958793fd7d56f79e140bba70bcacc5fe15bf8c0b958793fd7d56f
linuxlinux>= 93ae6b01bafee8fa385aa25ee7ebdb40057f6abe < 900b444be493b7f404898c785d6605b177a093d0900b444be493b7f404898c785d6605b177a093d0
linuxlinux>= 93ae6b01bafee8fa385aa25ee7ebdb40057f6abe < fbc7e61195e23f744814e78524b73b59faa54ab4fbc7e61195e23f744814e78524b73b59faa54ab4
linuxlinux>= c4ab60a86c5ed7c0d727c6dc8cec352e16bc7f90 < 5289ac43b69c61a49c75720921f2008005a31c435289ac43b69c61a49c75720921f2008005a31c43
linuxlinux>= d5f7d3833b534f9e43e548461dba1e60aa82f587 < 04c50cc23a492c4d43fdaefc7c1ecc0ff6f7b82e04c50cc23a492c4d43fdaefc7c1ecc0ff6f7b82e
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel>= 0 < 6.12.21-16.12.21-1
linuxlinux_kernel>= 0 < 6.12.21-16.12.21-1
linuxlinux_kernel>= 0 < 6.8.0-84.846.8.0-84.84
linuxlinux_kernel>= 6.13 < 6.13.96.13.9
linuxlinux_kernel>= 6.2 < 6.6.856.6.85
linuxlinux_kernel>= 6.7 < 6.12.216.12.21

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv5.9MEDIUM
vendor_ubuntu5.9MEDIUM
vendor_debian5.5LOW
vendor_redhat5.5MEDIUM
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