{"id":"CVE-2026-93232","summary":"mm/hugetlb: fix boot panic with CONFIG_DEBUG_VM and HVO bootmem pages","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.","modified":"2026-09-25T03:48:53.696453446Z","published":"2026-09-24T15:29:22.699Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93232.json","cna_assigner":"Linux"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/2ddf429e25cf8415d9c308f07e64012026bd4d77"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c0caeceb0c3899dc42844d3979093b27d1434108"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/93xxx/CVE-2026-93232.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-93232"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"622026e87c4019e609010811757e31193cc23847"},{"fixed":"2ddf429e25cf8415d9c308f07e64012026bd4d77"},{"fixed":"c0caeceb0c3899dc42844d3979093b27d1434108"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-93232.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"7.1.0"},{"fixed":"7.2.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-93232.json"}}],"schema_version":"1.9.0"}