fkie_cve-2025-22013
Vulnerability from fkie_nvd
Published
2025-04-08 09:15
Modified
2025-10-28 17:16
Severity ?
Summary
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.
References
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | 6.14 | |
| linux | linux_kernel | 6.14 |
{
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"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Unconditionally save+flush host FPSIMD/SVE/SME state\n\nThere are several problems with the way hyp code lazily saves the host\u0027s\nFPSIMD/SVE state, including:\n\n* Host SVE being discarded unexpectedly due to inconsistent\n configuration of TIF_SVE and CPACR_ELx.ZEN. This has been seen to\n result in QEMU crashes where SVE is used by memmove(), as reported by\n Eric Auger:\n\n https://issues.redhat.com/browse/RHEL-68997\n\n* Host SVE state is discarded *after* modification by ptrace, which was an\n unintentional ptrace ABI change introduced with lazy discarding of SVE state.\n\n* The host FPMR value can be discarded when running a non-protected VM,\n where FPMR support is not exposed to a VM, and that VM uses\n FPSIMD/SVE. In these cases the hyp code does not save the host\u0027s FPMR\n before unbinding the host\u0027s FPSIMD/SVE/SME state, leaving a stale\n value in memory.\n\nAvoid these by eagerly saving and \"flushing\" the host\u0027s FPSIMD/SVE/SME\nstate when loading a vCPU such that KVM does not need to save any of the\nhost\u0027s FPSIMD/SVE/SME state. For clarity, fpsimd_kvm_prepare() is\nremoved and the necessary call to fpsimd_save_and_flush_cpu_state() is\nplaced in kvm_arch_vcpu_load_fp(). As \u0027fpsimd_state\u0027 and \u0027fpmr_ptr\u0027\nshould not be used, they are set to NULL; all uses of these will be\nremoved in subsequent patches.\n\nHistorical problems go back at least as far as v5.17, e.g. erroneous\nassumptions about TIF_SVE being clear in commit:\n\n 8383741ab2e773a9 (\"KVM: arm64: Get rid of host SVE tracking/saving\")\n\n... and so this eager save+flush probably needs to be backported to ALL\nstable trees."
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: KVM: arm64: Guardar y vaciar incondicionalmente el estado FPSIMD/SVE/SME del host Hay varios problemas con la forma en que el c\u00f3digo hyp guarda de forma diferida el estado FPSIMD/SVE del host, incluidos: * El SVE del host se descarta inesperadamente debido a una configuraci\u00f3n inconsistente de TIF_SVE y CPACR_ELx.ZEN. Se ha visto que esto da como resultado fallos de QEMU donde memmove() usa SVE, como lo inform\u00f3 Eric Auger: https://issues.redhat.com/browse/RHEL-68997 * El estado SVE del host se descarta *despu\u00e9s* de la modificaci\u00f3n por ptrace, que fue un cambio de ABI de ptrace no intencionado introducido con el descarte diferido del estado SVE. * El valor FPMR del host se puede descartar cuando se ejecuta una VM no protegida, donde la compatibilidad con FPMR no est\u00e1 expuesta a una VM y esa VM usa FPSIMD/SVE. En estos casos, el c\u00f3digo hyp no guarda el FPMR del host antes de desvincular su estado FPSIMD/SVE/SME, lo que deja un valor obsoleto en memoria. Para evitar esto, guarde y vac\u00ede el estado FPSIMD/SVE/SME del host al cargar una vCPU, de modo que KVM no tenga que guardar ninguno de sus estados. Para mayor claridad, se ha eliminado fpsimd_kvm_prepare() y la llamada necesaria a fpsimd_save_and_flush_cpu_state() se ha ubicado en kvm_arch_vcpu_load_fp(). Dado que \u0027fpsimd_state\u0027 y \u0027fpmr_ptr\u0027 no deben usarse, se establecen en NULL; todos sus usos se eliminar\u00e1n en parches posteriores. Los problemas hist\u00f3ricos se remontan al menos a la versi\u00f3n v5.17, por ejemplo, suposiciones err\u00f3neas acerca de que TIF_SVE est\u00e1 claro en el commit: 8383741ab2e773a9 (\"KVM: arm64: deshacerse del seguimiento/guardado de SVE del host\")... y por eso, este ansioso guardado y vaciado probablemente deba ser retrotra\u00eddo a TODOS los \u00e1rboles estables."
}
],
"id": "CVE-2025-22013",
"lastModified": "2025-10-28T17:16:03.533",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 5.5,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 3.6,
"source": "nvd@nist.gov",
"type": "Primary"
}
]
},
"published": "2025-04-08T09:15:25.643",
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Analyzed",
"weaknesses": [
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"value": "NVD-CWE-noinfo"
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],
"source": "nvd@nist.gov",
"type": "Primary"
}
]
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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