FKIE_CVE-2026-97525

Vulnerability from fkie_nvd - Published: 2026-09-25 11:17 - Updated: 2026-09-25 15:17
Severity
8.2 (High) - CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: x86/mm/pat: Allocate split page tables as kernel page tables A PTE is allocated directly without going through the standard page table allocation routines (such as pte_alloc_one_kernel()) when the CPA code splits a large page (__split_large_page()). This means the page table constructor is never called nor is the page table marked as a kernel page table. The former results in the folio associated with the page table not being marked as a page table (__pagetable_ctor() is never called thus neither is __folio_set_pgtable()) nor are statistics updated to reflect it (lruvec_stat_add_folio() is never called). The latter issue of failing to mark the page table as a kernel page table (ptdesc_set_kernel() is never called) is far more problematic. Since commit: 5ba2f0a15564 ("mm: introduce deferred freeing for kernel page tables") kernel page table freeing has been batched and since the subsequent commit: e37d5a2d60a3 ("iommu/sva: invalidate stale IOTLB entries for kernel address space") IOTLB cache entries for kernel page tables have been invalidated upon being freed. Since split page tables are freed without this invalidation, the IOTLB can contain stale entries for them. Resolve the issue by using the ordinary PTE allocation API at split time. This results in these kernel page tables invoking a page table constructor, and thus requires a page table destructor. Destructors are not always present, like for early allocated direct map page tables). Conditionally call pagetable_dtor_free() if the PG_table folio flag for the ptdesc is set, otherwise we free the page table via pagetable_free(). Regardless of which path is taken page tables marked as kernel page tables, which now includes split page tables, take the correct route through pagetable_free_kernel(). There is a user-visible side effect in that split page tables will appear in nr_page_table_pages in /proc/vmstat (as do other kernel page tables allocated after early boot), however this is a positive change. This issue started being markedly problematic after commit: 5ba2f0a15564 ("mm: introduce deferred freeing for kernel page tables") so choose this as the Fixes target. [ dhansen: rephrase in imperative mood ]
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/84e0cd79d57f06b872154eb5d8f610584133f260
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/922873cf4fc34124215070a8ad391bf831538bb9
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/9e4a3ec3411bb6bb59e3c1f29b75609f1e87aac4
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "arch/x86/mm/pat/set_memory.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "84e0cd79d57f06b872154eb5d8f610584133f260",
              "status": "affected",
              "version": "b3039c526f3e1744db0cbb7ae1f0213f5e27d3f4",
              "versionType": "git"
            },
            {
              "lessThan": "922873cf4fc34124215070a8ad391bf831538bb9",
              "status": "affected",
              "version": "5ba2f0a1556479638ac11a3c201421f5515e89f5",
              "versionType": "git"
            },
            {
              "lessThan": "9e4a3ec3411bb6bb59e3c1f29b75609f1e87aac4",
              "status": "affected",
              "version": "5ba2f0a1556479638ac11a3c201421f5515e89f5",
              "versionType": "git"
            },
            {
              "lessThan": "6.18.53",
              "status": "affected",
              "version": "6.18.7",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "arch/x86/mm/pat/set_memory.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": "6.18.*",
              "status": "unaffected",
              "version": "6.18.53",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.7",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc4",
              "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\nx86/mm/pat: Allocate split page tables as kernel page tables\n\nA PTE is allocated directly without going through the standard page table\nallocation routines (such as pte_alloc_one_kernel()) when the CPA code\nsplits a large page (__split_large_page()).\n\nThis means the page table constructor is never called nor is the page table\nmarked as a kernel page table.\n\nThe former results in the folio associated with the page table not being\nmarked as a page table (__pagetable_ctor() is never called thus neither is\n__folio_set_pgtable()) nor are statistics updated to reflect\nit (lruvec_stat_add_folio() is never called).\n\nThe latter issue of failing to mark the page table as a kernel page\ntable (ptdesc_set_kernel() is never called) is far more problematic.\n\nSince commit:\n\n  5ba2f0a15564 (\"mm: introduce deferred freeing for kernel page tables\")\n\nkernel page table freeing has been batched and since the\nsubsequent commit:\n\n  e37d5a2d60a3 (\"iommu/sva: invalidate stale IOTLB entries for kernel address space\")\n\nIOTLB cache entries for kernel page tables have been invalidated upon\nbeing freed.\n\nSince split page tables are freed without this invalidation, the IOTLB\ncan contain stale entries for them.\n\nResolve the issue by using the ordinary PTE allocation API at split time.\n\nThis results in these kernel page tables invoking a page table constructor,\nand thus requires a page table destructor.\n\nDestructors are not always present, like for early allocated direct map\npage tables). Conditionally call pagetable_dtor_free() if the PG_table\nfolio flag for the ptdesc is set, otherwise we free the page table via\npagetable_free().\n\nRegardless of which path is taken page tables marked as kernel page tables,\nwhich now includes split page tables, take the correct route through\npagetable_free_kernel().\n\nThere is a user-visible side effect in that split page tables will appear\nin nr_page_table_pages in /proc/vmstat (as do other kernel page tables\nallocated after early boot), however this is a positive change.\n\nThis issue started being markedly problematic after commit:\n\n  5ba2f0a15564 (\"mm: introduce deferred freeing for kernel page tables\")\n\nso choose this as the Fixes target.\n\n[ dhansen: rephrase in imperative mood ]"
    }
  ],
  "id": "CVE-2026-97525",
  "lastModified": "2026-09-25T15:17:57.917",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 8.2,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "HIGH",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.5,
        "impactScore": 6.0,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-09-25T11:17:02.647",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/84e0cd79d57f06b872154eb5d8f610584133f260"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/922873cf4fc34124215070a8ad391bf831538bb9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/9e4a3ec3411bb6bb59e3c1f29b75609f1e87aac4"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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