{"id":"CVE-2026-89961","summary":"powerpc/mm: fix wrong addr_pfn tracking in compound vmemmap population","details":"In the Linux kernel, the following vulnerability has been resolved:\n\npowerpc/mm: fix wrong addr_pfn tracking in compound vmemmap population\n\nvmemmap_populate_compound_pages() uses addr_pfn to determine the PFN\noffset within a compound page and to decide whether the current vmemmap\nslot should be populated as a head page mapping or should reuse a tail\npage mapping.\n\nHowever, addr_pfn is advanced manually in parallel with addr.  The loop\nitself progresses in vmemmap address space, so each PAGE_SIZE step in addr\ncovers PAGE_SIZE / sizeof(struct page) struct page slots.  Since addr_pfn\nis compared against nr_pages in data-PFN units, it should advance by the\nsame number of PFNs.  The existing manual increments do not match that and\ntherefore do not reliably track the PFN corresponding to the current addr.\n\nAs a result, pfn_offset can be computed from the wrong PFN and the code\ncan make the head/tail decision for the wrong compound-page position.\n\nFix this by deriving addr_pfn directly from the current vmemmap address\ninstead of carrying it as loop state.","modified":"2026-09-18T03:48:34.394521256Z","published":"2026-09-16T10:32:43.921Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89961.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/7968852a7ca3ce81477ec5b4494a28d612f35a97"},{"type":"WEB","url":"https://git.kernel.org/stable/c/89a4ae32764172468dea303eb6ae90fe6c859712"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9c914b7a0bd18834505c65f22225ce22c152b2d9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b96be860673f9fbbf12cdadb0b25fc4d6d4d207f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e163c7184acf36ac20a248498f4a16016057ca01"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89961.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89961"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"f2b79c0d79683d552369bb9a7282c1f0226fc566"},{"fixed":"b96be860673f9fbbf12cdadb0b25fc4d6d4d207f"},{"fixed":"e163c7184acf36ac20a248498f4a16016057ca01"},{"fixed":"9c914b7a0bd18834505c65f22225ce22c152b2d9"},{"fixed":"7968852a7ca3ce81477ec5b4494a28d612f35a97"},{"fixed":"89a4ae32764172468dea303eb6ae90fe6c859712"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89961.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.6.0"},{"fixed":"6.6.157"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.110"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.51"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89961.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}