FKIE_CVE-2026-68163

Vulnerability from fkie_nvd - Published: 2026-08-10 13:20 - Updated: 2026-08-17 05:18
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/page_vma_mapped: fix device-private PMD handling Commit 65edfda6f3f2 ("mm/rmap: extend rmap and migration support device-private entries") introduced the concept of device-private PMD entries, but did not correctly update the rmap walk code to account for them. As a result, when page_vma_mapped_walk() encounters device-private PMD entries, it takes no action other than to acquire the PMD lock and exit. However this is highly problematic for two reasons - firstly, device private entries possess a PFN so check_pmd() needs to be called to ensure an overlapping PFN range. Secondly, and more importantly, if PVMW_MIGRATION is set the caller assumes the returned entry is a migration entry, resulting in memory corruption when the caller tries to interpret the device private entry as such. In addition, commit 146287290023 ("mm/huge_memory: implement device-private THP splitting") allowed device private PMDs to be split like THP mappings, but again did not update this code path. As a result, we might race a PMD split prior to acquiring the PMD lock. This patch addresses all of these issues by invoking check_pmd(), ensuring PMVW_MIGRATION is not set and checks whether a split raced us we do for PMD THP and migration entries. Instead of checking for a subset of the cases after taking the pmd_lock(), put device-private along with pmd_trans_huge() and pmd_is_migration_entry(). Also remove thp_migration_supported() as it is already guarded by pmd_is_migration_entry(). [akpm@linux-foundation.org: fix Raspberry Pi 1 build, per David]
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ab6209f4b48a98ef14d6766acdb62aa9bb32e670
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f84ca9b1888d8fce7dfefe0e750fa971f8797486
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "mm/page_vma_mapped.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "ab6209f4b48a98ef14d6766acdb62aa9bb32e670",
              "status": "affected",
              "version": "65edfda6f3f2e58f757485a056e4f1775a1404a8",
              "versionType": "git"
            },
            {
              "lessThan": "f84ca9b1888d8fce7dfefe0e750fa971f8797486",
              "status": "affected",
              "version": "65edfda6f3f2e58f757485a056e4f1775a1404a8",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "mm/page_vma_mapped.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": "7.1.*",
              "status": "unaffected",
              "version": "7.1.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/page_vma_mapped: fix device-private PMD handling\n\nCommit 65edfda6f3f2 (\"mm/rmap: extend rmap and migration support\ndevice-private entries\") introduced the concept of device-private PMD\nentries, but did not correctly update the rmap walk code to account for\nthem.\n\nAs a result, when page_vma_mapped_walk() encounters device-private PMD\nentries, it takes no action other than to acquire the PMD lock and exit.\n\nHowever this is highly problematic for two reasons - firstly, device\nprivate entries possess a PFN so check_pmd() needs to be called to ensure\nan overlapping PFN range.\n\nSecondly, and more importantly, if PVMW_MIGRATION is set the caller\nassumes the returned entry is a migration entry, resulting in memory\ncorruption when the caller tries to interpret the device private entry as\nsuch.\n\nIn addition, commit 146287290023 (\"mm/huge_memory: implement\ndevice-private THP splitting\") allowed device private PMDs to be split\nlike THP mappings, but again did not update this code path.\n\nAs a result, we might race a PMD split prior to acquiring the PMD lock.\n\nThis patch addresses all of these issues by invoking check_pmd(), ensuring\nPMVW_MIGRATION is not set and checks whether a split raced us we do for\nPMD THP and migration entries.\n\nInstead of checking for a subset of the cases after taking the pmd_lock(),\nput device-private along with pmd_trans_huge() and\npmd_is_migration_entry().  Also remove thp_migration_supported() as it is\nalready guarded by pmd_is_migration_entry().\n\n[akpm@linux-foundation.org: fix Raspberry Pi 1 build, per David]"
    }
  ],
  "id": "CVE-2026-68163",
  "lastModified": "2026-08-17T05:18:16.830",
  "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": "2026-08-10T13:20:02.720",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ab6209f4b48a98ef14d6766acdb62aa9bb32e670"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f84ca9b1888d8fce7dfefe0e750fa971f8797486"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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