GHSA-RJQQ-V75C-FV5F
Vulnerability from github – Published: 2026-09-24 18:31 – Updated: 2026-09-24 18:31In the Linux kernel, the following vulnerability has been resolved:
mm/hugetlb: fix boot panic with CONFIG_DEBUG_VM and HVO bootmem pages
Patch series "mm: Refactor bootmem gigantic hugepage allocation", v4.
This series is split out from the earlier larger series "mm: Generalize HVO for HugeTLB and device DAX" [1]. It collects the first 19 patches of that series as a standalone set of fixes and preparatory cleanups around bootmem HugeTLB handling, sparse initialization ordering, and related vmemmap setup.
The first patches fix a few bugs found while reviewing the existing code, including incorrect bootmem HVO handling, wrong vmemmap registration arguments, a powerpc compound-vmemmap tracking bug, and too-late initialization of gigantic bootmem HugeTLB struct pages.
The rest of the series reorders early memory initialization so the relevant zone state is available before sparse and HugeTLB boot-time setup runs, then simplifies the remaining bootmem gigantic hugepage allocation path and removes code made obsolete by that rework.
At a high level: - patches [1-4] fix boot-time and arch-specific bugs - patches [5-12] reorder and simplify sparse/mm/hugetlb early init - patches [13-19] refactor bootmem gigantic hugepage allocation and remove obsolete helpers and state
This patch (of 19):
Commit 622026e87c40 ("mm/hugetlb: remove fake head pages") switched HVO to reuse per-zone shared tail pages from zone->vmemmap_tails[].
Those shared tail pages were initialized in hugetlb_vmemmap_init(), but bootmem HugeTLB folios are prepared earlier from gather_bootmem_prealloc(). With hugetlb_free_vmemmap=on, prep_and_add_bootmem_folios() can access pageblock flags on bootmem HugeTLB pages whose mirrored tail struct pages already point to the shared tail page. On CONFIG_DEBUG_VM kernels, get_pfnblock_bitmap_bitidx() then dereferences the still-uninitialized shared tail page and can panic during boot.
Initialize zone->vmemmap_tails[] from gather_bootmem_prealloc(), before bootmem HugeTLB folios are processed, and drop the later initialization from hugetlb_vmemmap_init().
This bug only affects CONFIG_DEBUG_VM kernels, where the relevant assertion is evaluated.
{
"affected": [],
"aliases": [
"CVE-2026-93232"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-09-24T16:17:18Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/hugetlb: fix boot panic with CONFIG_DEBUG_VM and HVO bootmem pages\n\nPatch series \"mm: Refactor bootmem gigantic hugepage allocation\", v4.\n\nThis series is split out from the earlier larger series \"mm: Generalize\nHVO for HugeTLB and device DAX\" [1]. It collects the first 19 patches of\nthat series as a standalone set of fixes and preparatory cleanups around\nbootmem HugeTLB handling, sparse initialization ordering, and related\nvmemmap setup.\n\nThe first patches fix a few bugs found while reviewing the existing code,\nincluding incorrect bootmem HVO handling, wrong vmemmap registration\narguments, a powerpc compound-vmemmap tracking bug, and too-late\ninitialization of gigantic bootmem HugeTLB struct pages.\n\nThe rest of the series reorders early memory initialization so the\nrelevant zone state is available before sparse and HugeTLB boot-time setup\nruns, then simplifies the remaining bootmem gigantic hugepage allocation\npath and removes code made obsolete by that rework.\n\nAt a high level:\n - patches [1-4] fix boot-time and arch-specific bugs\n - patches [5-12] reorder and simplify sparse/mm/hugetlb early init\n - patches [13-19] refactor bootmem gigantic hugepage allocation and\n remove obsolete helpers and state\n\n\nThis patch (of 19):\n\nCommit 622026e87c40 (\"mm/hugetlb: remove fake head pages\") switched\nHVO to reuse per-zone shared tail pages from zone-\u003evmemmap_tails[].\n\nThose shared tail pages were initialized in hugetlb_vmemmap_init(), but\nbootmem HugeTLB folios are prepared earlier from\ngather_bootmem_prealloc(). With hugetlb_free_vmemmap=on,\nprep_and_add_bootmem_folios() can access pageblock flags on bootmem\nHugeTLB pages whose mirrored tail struct pages already point to the shared\ntail page. On CONFIG_DEBUG_VM kernels, get_pfnblock_bitmap_bitidx() then\ndereferences the still-uninitialized shared tail page and can panic during\nboot.\n\nInitialize zone-\u003evmemmap_tails[] from gather_bootmem_prealloc(), before\nbootmem HugeTLB folios are processed, and drop the later initialization\nfrom hugetlb_vmemmap_init().\n\nThis bug only affects CONFIG_DEBUG_VM kernels, where the relevant\nassertion is evaluated.",
"id": "GHSA-rjqq-v75c-fv5f",
"modified": "2026-09-24T18:31:23Z",
"published": "2026-09-24T18:31:23Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-93232"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/2ddf429e25cf8415d9c308f07e64012026bd4d77"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c0caeceb0c3899dc42844d3979093b27d1434108"
}
],
"schema_version": "1.4.0",
"severity": []
}
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