GHSA-4Q4Q-JV3M-FQJR

Vulnerability from github – Published: 2025-05-08 09:30 – Updated: 2025-11-13 00:30
VLAI
Details

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.

Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2025-37818"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-476"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-05-08T07:15:53Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nLoongArch: Return NULL from huge_pte_offset() for invalid PMD\n\nLoongArch\u0027s huge_pte_offset() currently returns a pointer to a PMD slot\neven if the underlying entry points to invalid_pte_table (indicating no\nmapping). Callers like smaps_hugetlb_range() fetch this invalid entry\nvalue (the address of invalid_pte_table) via this pointer.\n\nThe generic is_swap_pte() check then incorrectly identifies this address\nas a swap entry on LoongArch, because it satisfies the \"!pte_present()\n\u0026\u0026 !pte_none()\" conditions. This misinterpretation, combined with a\ncoincidental match by is_migration_entry() on the address bits, leads to\nkernel crashes in pfn_swap_entry_to_page().\n\nFix this at the architecture level by modifying huge_pte_offset() to\ncheck the PMD entry\u0027s content using pmd_none() before returning. If the\nentry is invalid (i.e., it points to invalid_pte_table), return NULL\ninstead of the pointer to the slot.",
  "id": "GHSA-4q4q-jv3m-fqjr",
  "modified": "2025-11-13T00:30:16Z",
  "published": "2025-05-08T09:30:24Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-37818"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2ca9380b12711afe95b3589bd82b59623b3c96b3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/34256805720993e37adf6127371a1265aea8376a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/51424fd171cee6a33f01f7c66b8eb23ac42289d4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b49f085cd671addbda4802d6b9382513f7dd0f30"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bd51834d1cf65a2c801295d230c220aeebf87a73"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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