{ "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": "2026-10-19T08:52:11.845Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:52:11.845Z" }, "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", "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" } ] } ] } ], "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" } } } }