CVE-2026-89758 (GCVE-0-2026-89758)
Vulnerability from cvelistv5
Published
2026-09-11 19:47
Modified
2026-10-19 08:52
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: mm/mempolicy: skip non-present PMDs when queueing folios Patch series "mm: handle device-private PMDs in walk callbacks", v3. Since commit 368076f52ebe ("mm/huge_memory: add device-private THP support to PMD operations") a PMD may hold a device-private swap entry whenever an HMM-based GPU driver migrates an anonymous THP folio to device memory via migrate_vma_pages(). pmd_trans_huge_lock() succeeds for such PMDs (pmd_is_huge() returns true for any non-present, non-none huge PMD), so several MM walk callbacks that used to assume present THP or migration entry are now reachable with a device-private PMD. The results range from a VM_BUG_ON() firing on debug kernels, to an oops on a bogus vmemmap dereference, to silently isolating an unrelated live folio from LRU in the aliasing case. This patch (of 3): queue_folios_pmd() is called under pmd_trans_huge_lock(), whose pmd_is_huge() check returns true for any non-present, non-none PMD softleaf. Passing such a PMD to pmd_folio() treats the softleaf encoding as a hardware PFN and can return a bogus folio pointer. Mirror queue_folios_pte_range(): handle non-present entries before looking up a folio. Keep migration entries counted as failures, but skip other non-present PMDs such as device-private entries. Potential trigger: an HMM-based GPU driver migrates an anonymous THP folio to device memory via migrate_vma_pages(), leaving a device-private PMD. Userspace then calls mbind(), migrate_pages() or set_mempolicy_home_node() on that range.
References
Impacted products
Vendor Product Version
Linux Linux Version: 368076f52ebeecd33e10a9f80905d7508b6b6149
Version: 368076f52ebeecd33e10a9f80905d7508b6b6149
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "mm/mempolicy.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "versionType": "git"
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              "status": "affected",
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              "versionType": "git"
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        {
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          "product": "Linux",
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            "mm/mempolicy.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.19"
            },
            {
              "lessThan": "6.19",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.4",
                  "versionStartIncluding": "6.19",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "6.19",
                  "vulnerable": true
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              ],
              "negate": false,
              "operator": "OR"
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        }
      ],
      "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": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - queue_folios_pmd() is reached only from local mbind() and migrate_pages() via do_mbind()/do_migrate_pages() -\u003e queue_pages_range() -\u003e 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."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:52:11.845Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "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"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89758",
    "datePublished": "2026-09-11T19:47:00.562Z",
    "dateReserved": "2026-09-11T19:38:34.763Z",
    "dateUpdated": "2026-10-19T08:52:11.845Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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