{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89758","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-11T19:38:34.763Z","datePublished":"2026-09-11T19:47:00.562Z","dateUpdated":"2026-09-13T06:34:02.653Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-13T06:34:02.653Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/mempolicy: skip non-present PMDs when queueing folios\n\nPatch series \"mm: handle device-private PMDs in walk callbacks\", v3.\n\nSince commit 368076f52ebe (\"mm/huge_memory: add device-private THP support\nto PMD operations\") a PMD may hold a device-private swap entry whenever an\nHMM-based GPU driver migrates an anonymous THP folio to device memory via\nmigrate_vma_pages().\n\npmd_trans_huge_lock() succeeds for such PMDs (pmd_is_huge() returns true\nfor any non-present, non-none huge PMD), so several MM walk callbacks that\nused to assume present THP or migration entry are now reachable with a\ndevice-private PMD.  The results range from a VM_BUG_ON() firing on debug\nkernels, to an oops on a bogus vmemmap dereference, to silently isolating\nan unrelated live folio from LRU in the aliasing case.\n\n\nThis patch (of 3):\n\nqueue_folios_pmd() is called under pmd_trans_huge_lock(), whose\npmd_is_huge() check returns true for any non-present, non-none PMD\nsoftleaf.  Passing such a PMD to pmd_folio() treats the softleaf encoding\nas a hardware PFN and can return a bogus folio pointer.\n\nMirror queue_folios_pte_range(): handle non-present entries before looking\nup a folio.  Keep migration entries counted as failures, but skip other\nnon-present PMDs such as device-private entries.\n\nPotential trigger: an HMM-based GPU driver migrates an anonymous THP folio\nto device memory via migrate_vma_pages(), leaving a device-private PMD. \nUserspace then calls mbind(), migrate_pages() or set_mempolicy_home_node()\non that range."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - queue_folios_pmd() is reached only from local mbind() and migrate_pages() via do_mbind()/do_migrate_pages() -> queue_pages_range() -> walk_page_range(); it is not a network, Bluetooth, or USB packet path.\nAC:L - An attacker with GPU/HMM access can deterministically migrate an anonymous THP to device memory (leaving a device-private PMD) and then call mbind()/migrate_pages() on that range; no victim state or attacker-uncontrollable race is required.\nPR:L - mbind() and self migrate_pages() are unprivileged; MPOL_MF_MOVE needs no capability. Device-private THP is created through ordinary DRM render-node/HMM usage (AMD KFD, Intel Xe, nouveau), not init-namespace root.\nUI:N - The attacker creates the device-private THP mapping and issues mbind() or migrate_pages() entirely in their own process; no other user must mount, open, or otherwise act.\nS:U - Impact is host-kernel MM corruption (bogus folio lookup and LRU isolation) within the same security authority; it is not a VM guest-to-host escape, IOMMU bypass, or sandbox breakout.\nC:H - pmd_folio() treats a device-private PMD as a present THP and returns a bogus folio; aliasing isolates and migrates an unrelated live folio, a memory-corruption primitive usable for arbitrary kernel/user memory disclosure.\nI:H - The same bogus folio can be isolated from the LRU and handed to migrate_pages(), silently moving an unrelated live folio and enabling use-after-free, page-table corruption, and control-flow hijack.\nA:H - A bogus vmemmap dereference oopses the kernel, debug builds hit VM_BUG_ON, and isolating or migrating the wrong folio can panic or hang the system."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/mempolicy.c"],"versions":[{"version":"368076f52ebeecd33e10a9f80905d7508b6b6149","lessThan":"3d927093b2add7ced588a926c3dc5d7a83f18596","status":"affected","versionType":"git"},{"version":"368076f52ebeecd33e10a9f80905d7508b6b6149","lessThan":"2858b4027f491e6fdb8ee2d8923798b619bf2791","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["mm/mempolicy.c"],"versions":[{"version":"6.19","status":"affected"},{"version":"0","lessThan":"6.19","status":"unaffected","versionType":"semver"},{"version":"7.2.4","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3-rc1","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.19","versionEndExcluding":"7.2.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.19","versionEndExcluding":"7.3-rc1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/3d927093b2add7ced588a926c3dc5d7a83f18596"},{"url":"https://git.kernel.org/stable/c/2858b4027f491e6fdb8ee2d8923798b619bf2791"}],"title":"mm/mempolicy: skip non-present PMDs when queueing folios","x_generator":{"engine":"bippy-1.2.0"}}}}