GHSA-7JF9-69M7-87P6
Vulnerability from github – Published: 2025-04-08 09:31 – Updated: 2025-10-28 18:30In 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": [],
"aliases": [
"CVE-2025-22013"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-04-08T09:15:25Z",
"severity": "MODERATE"
},
"details": "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.",
"id": "GHSA-7jf9-69m7-87p6",
"modified": "2025-10-28T18:30:24Z",
"published": "2025-04-08T09:31:12Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-22013"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/04c50cc23a492c4d43fdaefc7c1ecc0ff6f7b82e"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5289ac43b69c61a49c75720921f2008005a31c43"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/79e140bba70bcacc5fe15bf8c0b958793fd7d56f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/806d5c1e1d2e5502175a24bf70f251648d99c36a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/900b444be493b7f404898c785d6605b177a093d0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fbc7e61195e23f744814e78524b73b59faa54ab4"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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