GHSA-CMCR-4938-MJGJ
Vulnerability from github – Published: 2024-05-22 09:31 – Updated: 2025-09-24 03:30In the Linux kernel, the following vulnerability has been resolved:
KVM: arm64: Fix host stage-2 PGD refcount
The KVM page-table library refcounts the pages of concatenated stage-2 PGDs individually. However, when running KVM in protected mode, the host's stage-2 PGD is currently managed by EL2 as a single high-order compound page, which can cause the refcount of the tail pages to reach 0 when they shouldn't, hence corrupting the page-table.
Fix this by introducing a new hyp_split_page() helper in the EL2 page allocator (matching the kernel's split_page() function), and make use of it from host_s2_zalloc_pages_exact().
{
"affected": [],
"aliases": [
"CVE-2021-47450"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-05-22T07:15:10Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nKVM: arm64: Fix host stage-2 PGD refcount\n\nThe KVM page-table library refcounts the pages of concatenated stage-2\nPGDs individually. However, when running KVM in protected mode, the\nhost\u0027s stage-2 PGD is currently managed by EL2 as a single high-order\ncompound page, which can cause the refcount of the tail pages to reach 0\nwhen they shouldn\u0027t, hence corrupting the page-table.\n\nFix this by introducing a new hyp_split_page() helper in the EL2 page\nallocator (matching the kernel\u0027s split_page() function), and make use of\nit from host_s2_zalloc_pages_exact().",
"id": "GHSA-cmcr-4938-mjgj",
"modified": "2025-09-24T03:30:25Z",
"published": "2024-05-22T09:31:45Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2021-47450"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1d58a17ef54599506d44c45ac95be27273a4d2b1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b372264c66ef78f2cab44e877fbd765ad6d24c39"
}
],
"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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