FKIE_CVE-2026-31397

Vulnerability from fkie_nvd - Published: 2026-04-03 16:16 - Updated: 2026-07-24 22:10
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/huge_memory: fix use of NULL folio in move_pages_huge_pmd() move_pages_huge_pmd() handles UFFDIO_MOVE for both normal THPs and huge zero pages. For the huge zero page path, src_folio is explicitly set to NULL, and is used as a sentinel to skip folio operations like lock and rmap. In the huge zero page branch, src_folio is NULL, so folio_mk_pmd(NULL, pgprot) passes NULL through folio_pfn() and page_to_pfn(). With SPARSEMEM_VMEMMAP this silently produces a bogus PFN, installing a PMD pointing to non-existent physical memory. On other memory models it is a NULL dereference. Use page_folio(src_page) to obtain the valid huge zero folio from the page, which was obtained from pmd_page() and remains valid throughout. After commit d82d09e48219 ("mm/huge_memory: mark PMD mappings of the huge zero folio special"), moved huge zero PMDs must remain special so vm_normal_page_pmd() continues to treat them as special mappings. move_pages_huge_pmd() currently reconstructs the destination PMD in the huge zero page branch, which drops PMD state such as pmd_special() on architectures with CONFIG_ARCH_HAS_PTE_SPECIAL. As a result, vm_normal_page_pmd() can treat the moved huge zero PMD as a normal page and corrupt its refcount. Instead of reconstructing the PMD from the folio, derive the destination entry from src_pmdval after pmdp_huge_clear_flush(), then handle the PMD metadata the same way move_huge_pmd() does for moved entries by marking it soft-dirty and clearing uffd-wp.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e3133d0986dc5a231d5419167dbac65312b28b41Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f3caaee0f9e489fd2282d4ce45791dc8aed2da62Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fae654083bfa409bb2244f390232e2be47f05bfcPatch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "mm/huge_memory.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f3caaee0f9e489fd2282d4ce45791dc8aed2da62",
              "status": "affected",
              "version": "e3981db444a0a18d350d9f92e3f2e8d489b54211",
              "versionType": "git"
            },
            {
              "lessThan": "e3133d0986dc5a231d5419167dbac65312b28b41",
              "status": "affected",
              "version": "e3981db444a0a18d350d9f92e3f2e8d489b54211",
              "versionType": "git"
            },
            {
              "lessThan": "fae654083bfa409bb2244f390232e2be47f05bfc",
              "status": "affected",
              "version": "e3981db444a0a18d350d9f92e3f2e8d489b54211",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "mm/huge_memory.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.16"
            },
            {
              "lessThan": "6.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.20",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
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              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "1C570CE1-BC61-4BE6-9393-FD0CA8637367",
              "versionEndExcluding": "6.18.20",
              "versionStartIncluding": "6.16",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "96D34333-38BE-4414-9E79-6EB764329581",
              "versionEndExcluding": "6.19.10",
              "versionStartIncluding": "6.19",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*",
              "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16",
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              "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*",
              "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*",
              "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2",
              "vulnerable": true
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          "negate": false,
          "operator": "OR"
        }
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  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/huge_memory: fix use of NULL folio in move_pages_huge_pmd()\n\nmove_pages_huge_pmd() handles UFFDIO_MOVE for both normal THPs and huge\nzero pages.  For the huge zero page path, src_folio is explicitly set to\nNULL, and is used as a sentinel to skip folio operations like lock and\nrmap.\n\nIn the huge zero page branch, src_folio is NULL, so folio_mk_pmd(NULL,\npgprot) passes NULL through folio_pfn() and page_to_pfn().  With\nSPARSEMEM_VMEMMAP this silently produces a bogus PFN, installing a PMD\npointing to non-existent physical memory.  On other memory models it is a\nNULL dereference.\n\nUse page_folio(src_page) to obtain the valid huge zero folio from the\npage, which was obtained from pmd_page() and remains valid throughout.\n\nAfter commit d82d09e48219 (\"mm/huge_memory: mark PMD mappings of the huge\nzero folio special\"), moved huge zero PMDs must remain special so\nvm_normal_page_pmd() continues to treat them as special mappings.\n\nmove_pages_huge_pmd() currently reconstructs the destination PMD in the\nhuge zero page branch, which drops PMD state such as pmd_special() on\narchitectures with CONFIG_ARCH_HAS_PTE_SPECIAL.  As a result,\nvm_normal_page_pmd() can treat the moved huge zero PMD as a normal page\nand corrupt its refcount.\n\nInstead of reconstructing the PMD from the folio, derive the destination\nentry from src_pmdval after pmdp_huge_clear_flush(), then handle the PMD\nmetadata the same way move_huge_pmd() does for moved entries by marking it\nsoft-dirty and clearing uffd-wp."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nmm/huge_memory: corrige el uso de folio NULL en move_pages_huge_pmd()\n\nmove_pages_huge_pmd() maneja UFFDIO_MOVE tanto para THPs normales como para p\u00e1ginas cero enormes. Para la ruta de la p\u00e1gina cero enorme, src_folio se establece expl\u00edcitamente en NULL, y se usa como un centinela para omitir operaciones de folio como lock y rmap.\n\nEn la rama de la p\u00e1gina cero enorme, src_folio es NULL, por lo que folio_mk_pmd(NULL, pgprot) pasa NULL a trav\u00e9s de folio_pfn() y page_to_pfn(). Con SPARSEMEM_VMEMMAP esto produce silenciosamente un PFN err\u00f3neo, instalando un PMD que apunta a memoria f\u00edsica inexistente. En otros modelos de memoria es una desreferencia NULL.\n\nUsar page_folio(src_page) para obtener el folio cero enorme v\u00e1lido de la p\u00e1gina, que se obtuvo de pmd_page() y permanece v\u00e1lido en todo momento.\n\nDespu\u00e9s del commit d82d09e48219 (\u0027mm/huge_memory: marcar las asignaciones PMD del folio cero enorme como especiales\u0027), los PMD cero enormes movidos deben permanecer especiales para que vm_normal_page_pmd() contin\u00fae trat\u00e1ndolos como asignaciones especiales.\n\nmove_pages_huge_pmd() actualmente reconstruye el PMD de destino en la rama de la p\u00e1gina cero enorme, lo que elimina el estado del PMD como pmd_special() en arquitecturas con CONFIG_ARCH_HAS_PTE_SPECIAL. Como resultado, vm_normal_page_pmd() puede tratar el PMD cero enorme movido como una p\u00e1gina normal y corromper su refcount.\n\nEn lugar de reconstruir el PMD a partir del folio, derivar la entrada de destino de src_pmdval despu\u00e9s de pmdp_huge_clear_flush(), luego manejar los metadatos del PMD de la misma manera que move_huge_pmd() lo hace para las entradas movidas, marc\u00e1ndolo como soft-dirty y borrando uffd-wp."
    }
  ],
  "id": "CVE-2026-31397",
  "lastModified": "2026-07-24T22:10:00.140",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-04-03T16:16:38.093",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/e3133d0986dc5a231d5419167dbac65312b28b41"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/f3caaee0f9e489fd2282d4ce45791dc8aed2da62"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/fae654083bfa409bb2244f390232e2be47f05bfc"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-476"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}



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