LoongArch: Return NULL from huge_pte_offset() for invalid PMD

{
  "id": "d2f451e58c2eb79149339395f32b6ac83b8f5a0e92771ddcb91934da55fe42d3",
  "url": "https://osv.dev/vulnerability/CVE-2025-37818",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "LoongArch: Return NULL from huge_pte_offset() for invalid PMD",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: LoongArch: Return NULL from huge_pte_offset() for invalid PMD LoongArch's huge_pte_offset() currently returns a pointer to a PMD slot even if the underlying entry points to invalid_pte_table (indicating no mapping). Callers like smaps_hugetlb_range() fetch this invalid entry value (the address of invalid_pte_table) via this pointer. The generic is_swap_pte() check then incorrectly identifies this address as a swap entry on LoongArch, because it satisfies the \"!pte_present() && !pte_none()\" conditions. This misinterpretation, combined with a coincidental match by is_migration_entry() on the address bits, leads to kernel crashes in pfn_swap_entry_to_page(). Fix this at the architecture level by modifying huge_pte_offset() to check the PMD entry's content using pmd_none() before returning. If the entry is invalid (i.e., it points to invalid_pte_table), return NULL instead of the pointer to the slot.",
    "evidence": "osv:CVE-2025-37818",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.136",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.89",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.26",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.14.5",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2025-37818",
      "aliases": [
        "CVE-2025-37818"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "fa96b57c149061f71a70bd6582d995f6424fbbf4"
                },
                {
                  "fixed": "34256805720993e37adf6127371a1265aea8376a"
                },
                {
                  "fixed": "2ca9380b12711afe95b3589bd82b59623b3c96b3"
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                {
                  "fixed": "51424fd171cee6a33f01f7c66b8eb23ac42289d4"
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                {
                  "fixed": "b49f085cd671addbda4802d6b9382513f7dd0f30"
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                {
                  "fixed": "bd51834d1cf65a2c801295d230c220aeebf87a73"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-37818.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.19.0"
                },
                {
                  "fixed": "6.1.136"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.2.0"
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                {
                  "fixed": "6.6.89"
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            {
              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "6.7.0"
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                {
                  "fixed": "6.12.26"
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              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.14.5"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-37818.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:26.477466229Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/2ca9380b12711afe95b3589bd82b59623b3c96b3",
        "https://git.kernel.org/stable/c/34256805720993e37adf6127371a1265aea8376a",
        "https://git.kernel.org/stable/c/51424fd171cee6a33f01f7c66b8eb23ac42289d4",
        "https://git.kernel.org/stable/c/b49f085cd671addbda4802d6b9382513f7dd0f30",
        "https://git.kernel.org/stable/c/bd51834d1cf65a2c801295d230c220aeebf87a73",
        "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/37xxx/CVE-2025-37818.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-37818",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/37xxx/CVE-2025-37818.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-37818",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 492711,
  "published_at": "2025-05-08T06:26:13.322+00:00"
}