FKIE_CVE-2026-43486

Vulnerability from fkie_nvd - Published: 2026-05-13 16:16 - Updated: 2026-06-26 19:23
Severity
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: arm64: contpte: fix set_access_flags() no-op check for SMMU/ATS faults contpte_ptep_set_access_flags() compared the gathered ptep_get() value against the requested entry to detect no-ops. ptep_get() ORs AF/dirty from all sub-PTEs in the CONT block, so a dirty sibling can make the target appear already-dirty. When the gathered value matches entry, the function returns 0 even though the target sub-PTE still has PTE_RDONLY set in hardware. For a CPU with FEAT_HAFDBS this gathered view is fine, since hardware may set AF/dirty on any sub-PTE and CPU TLB behavior is effectively gathered across the CONT range. But page-table walkers that evaluate each descriptor individually (e.g. a CPU without DBM support, or an SMMU without HTTU, or with HA/HD disabled in CD.TCR) can keep faulting on the unchanged target sub-PTE, causing an infinite fault loop. Gathering can therefore cause false no-ops when only a sibling has been updated: - write faults: target still has PTE_RDONLY (needs PTE_RDONLY cleared) - read faults: target still lacks PTE_AF Fix by checking each sub-PTE against the requested AF/dirty/write state (the same bits consumed by __ptep_set_access_flags()), using raw per-PTE values rather than the gathered ptep_get() view, before returning no-op. Keep using the raw target PTE for the write-bit unfold decision. Per Arm ARM (DDI 0487) D8.7.1 ("The Contiguous bit"), any sub-PTE in a CONT range may become the effective cached translation and software must maintain consistent attributes across the range.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/05d239f2c95e66e27e7fb4e99ee07eb56e3e34b0Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/09d620555e59768776090073a2c59d2bc8506eb3Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6f92a7a8b48a523f910ef25dd83808710724f59bPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/97c5550b763171dbef61e6239cab372b9f9cd4a2Patch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel 7.0
linux linux_kernel 7.0
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/mm/contpte.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "05d239f2c95e66e27e7fb4e99ee07eb56e3e34b0",
              "status": "affected",
              "version": "4602e5757bcceb231c3a13c36c373ad4a750eddb",
              "versionType": "git"
            },
            {
              "lessThan": "6f92a7a8b48a523f910ef25dd83808710724f59b",
              "status": "affected",
              "version": "4602e5757bcceb231c3a13c36c373ad4a750eddb",
              "versionType": "git"
            },
            {
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              "status": "affected",
              "version": "4602e5757bcceb231c3a13c36c373ad4a750eddb",
              "versionType": "git"
            },
            {
              "lessThan": "97c5550b763171dbef61e6239cab372b9f9cd4a2",
              "status": "affected",
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              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/arm64/mm/contpte.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.9"
            },
            {
              "lessThan": "6.9",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.78",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.19",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.9",
              "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": "D1D90B78-24E3-418D-A238-3FE23C32239B",
              "versionEndExcluding": "6.12.78",
              "versionStartIncluding": "6.9",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "D394AC60-6F28-435F-872A-CCDF384B8331",
              "versionEndExcluding": "6.18.19",
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              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "E825E7C3-FEAC-4FD3-8A81-78D7387948C9",
              "versionEndExcluding": "6.19.9",
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              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*",
              "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*",
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            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\narm64: contpte: fix set_access_flags() no-op check for SMMU/ATS faults\n\ncontpte_ptep_set_access_flags() compared the gathered ptep_get() value\nagainst the requested entry to detect no-ops. ptep_get() ORs AF/dirty\nfrom all sub-PTEs in the CONT block, so a dirty sibling can make the\ntarget appear already-dirty. When the gathered value matches entry, the\nfunction returns 0 even though the target sub-PTE still has PTE_RDONLY\nset in hardware.\n\nFor a CPU with FEAT_HAFDBS this gathered view is fine, since hardware may\nset AF/dirty on any sub-PTE and CPU TLB behavior is effectively gathered\nacross the CONT range. But page-table walkers that evaluate each\ndescriptor individually (e.g. a CPU without DBM support, or an SMMU\nwithout HTTU, or with HA/HD disabled in CD.TCR) can keep faulting on the\nunchanged target sub-PTE, causing an infinite fault loop.\n\nGathering can therefore cause false no-ops when only a sibling has been\nupdated:\n - write faults: target still has PTE_RDONLY (needs PTE_RDONLY cleared)\n - read faults:  target still lacks PTE_AF\n\nFix by checking each sub-PTE against the requested AF/dirty/write state\n(the same bits consumed by __ptep_set_access_flags()), using raw\nper-PTE values rather than the gathered ptep_get() view, before\nreturning no-op. Keep using the raw target PTE for the write-bit unfold\ndecision.\n\nPer Arm ARM (DDI 0487) D8.7.1 (\"The Contiguous bit\"), any sub-PTE in a CONT\nrange may become the effective cached translation and software must\nmaintain consistent attributes across the range."
    }
  ],
  "id": "CVE-2026-43486",
  "lastModified": "2026-06-26T19:23:45.627",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2026-05-13T16:16:51.880",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/05d239f2c95e66e27e7fb4e99ee07eb56e3e34b0"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/09d620555e59768776090073a2c59d2bc8506eb3"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/6f92a7a8b48a523f910ef25dd83808710724f59b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/97c5550b763171dbef61e6239cab372b9f9cd4a2"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-835"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}


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