{"id":"CVE-2026-89961","published":"2026-09-16T11:17:06.570","lastModified":"2026-09-16T15:18:20.703","description":"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.","cvssScore":7.8,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/7968852a7ca3ce81477ec5b4494a28d612f35a97","tags":[]},{"url":"https://git.kernel.org/stable/c/89a4ae32764172468dea303eb6ae90fe6c859712","tags":[]},{"url":"https://git.kernel.org/stable/c/9c914b7a0bd18834505c65f22225ce22c152b2d9","tags":[]},{"url":"https://git.kernel.org/stable/c/b96be860673f9fbbf12cdadb0b25fc4d6d4d207f","tags":[]},{"url":"https://git.kernel.org/stable/c/e163c7184acf36ac20a248498f4a16016057ca01","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":{"summary":"The flaw involves incorrect tracking of addr_pfn in the vmemmap_populate_compound_pages() function, leading to potential misidentification of head and tail page mappings for compound pages. This can result in security vulnerabilities such as unauthorized access or data corruption.","exploitability":"Exploiting this vulnerability requires low privileges and involves complex memory manipulation. Precondition is the presence of compound pages in the memory layout.","blast_radius":"If exploited, the impact could be high, potentially leading to unauthorized access or data corruption within the system.","remediation":"Upgrade to the Linux kernel version 6.1.17 or later.","detection":"No reliable host or network indicator is derivable from the published description.","tags":["memory","kernel","privilege","compound-pages"],"model":"qwen2.5:7b-instruct","analyzedAt":"2026-10-08T08:42:59.716Z"}}