CVE-2025-39899 (GCVE-0-2025-39899)
Vulnerability from cvelistv5
Published
2025-10-01 07:42
Modified
2025-10-01 07:42
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: mm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE With CONFIG_HIGHPTE on 32-bit ARM, move_pages_pte() maps PTE pages using kmap_local_page(), which requires unmapping in Last-In-First-Out order. The current code maps dst_pte first, then src_pte, but unmaps them in the same order (dst_pte, src_pte), violating the LIFO requirement. This causes the warning in kunmap_local_indexed(): WARNING: CPU: 0 PID: 604 at mm/highmem.c:622 kunmap_local_indexed+0x178/0x17c addr \!= __fix_to_virt(FIX_KMAP_BEGIN + idx) Fix this by reversing the unmap order to respect LIFO ordering. This issue follows the same pattern as similar fixes: - commit eca6828403b8 ("crypto: skcipher - fix mismatch between mapping and unmapping order") - commit 8cf57c6df818 ("nilfs2: eliminate staggered calls to kunmap in nilfs_rename") Both of which addressed the same fundamental requirement that kmap_local operations must follow LIFO ordering.
References
Impacted products
Vendor Product Version
Linux Linux Version: adef440691bab824e39c1b17382322d195e1fab0
Version: adef440691bab824e39c1b17382322d195e1fab0
Version: adef440691bab824e39c1b17382322d195e1fab0
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{
  "containers": {
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "mm/userfaultfd.c"
          ],
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          "vendor": "Linux",
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              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE\n\nWith CONFIG_HIGHPTE on 32-bit ARM, move_pages_pte() maps PTE pages using\nkmap_local_page(), which requires unmapping in Last-In-First-Out order.\n\nThe current code maps dst_pte first, then src_pte, but unmaps them in the\nsame order (dst_pte, src_pte), violating the LIFO requirement.  This\ncauses the warning in kunmap_local_indexed():\n\n  WARNING: CPU: 0 PID: 604 at mm/highmem.c:622 kunmap_local_indexed+0x178/0x17c\n  addr \\!= __fix_to_virt(FIX_KMAP_BEGIN + idx)\n\nFix this by reversing the unmap order to respect LIFO ordering.\n\nThis issue follows the same pattern as similar fixes:\n- commit eca6828403b8 (\"crypto: skcipher - fix mismatch between mapping and unmapping order\")\n- commit 8cf57c6df818 (\"nilfs2: eliminate staggered calls to kunmap in nilfs_rename\")\n\nBoth of which addressed the same fundamental requirement that kmap_local\noperations must follow LIFO ordering."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-10-01T07:42:47.100Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/b051f707018967ea8f697d790a1ed8c443f63812"
        },
        {
          "url": "https://git.kernel.org/stable/c/bd1ee62759d0bd4d6b909731c076c230ac89d61e"
        },
        {
          "url": "https://git.kernel.org/stable/c/9614d8bee66387501f48718fa306e17f2aa3f2f3"
        }
      ],
      "title": "mm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2025-39899",
    "datePublished": "2025-10-01T07:42:47.100Z",
    "dateReserved": "2025-04-16T07:20:57.146Z",
    "dateUpdated": "2025-10-01T07:42:47.100Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.1",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-39899\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-10-01T08:15:32.620\",\"lastModified\":\"2025-10-02T19:12:17.160\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nmm/userfaultfd: fix kmap_local LIFO ordering for CONFIG_HIGHPTE\\n\\nWith CONFIG_HIGHPTE on 32-bit ARM, move_pages_pte() maps PTE pages using\\nkmap_local_page(), which requires unmapping in Last-In-First-Out order.\\n\\nThe current code maps dst_pte first, then src_pte, but unmaps them in the\\nsame order (dst_pte, src_pte), violating the LIFO requirement.  This\\ncauses the warning in kunmap_local_indexed():\\n\\n  WARNING: CPU: 0 PID: 604 at mm/highmem.c:622 kunmap_local_indexed+0x178/0x17c\\n  addr \\\\!= __fix_to_virt(FIX_KMAP_BEGIN + idx)\\n\\nFix this by reversing the unmap order to respect LIFO ordering.\\n\\nThis issue follows the same pattern as similar fixes:\\n- commit eca6828403b8 (\\\"crypto: skcipher - fix mismatch between mapping and unmapping order\\\")\\n- commit 8cf57c6df818 (\\\"nilfs2: eliminate staggered calls to kunmap in nilfs_rename\\\")\\n\\nBoth of which addressed the same fundamental requirement that kmap_local\\noperations must follow LIFO ordering.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/9614d8bee66387501f48718fa306e17f2aa3f2f3\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b051f707018967ea8f697d790a1ed8c443f63812\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/bd1ee62759d0bd4d6b909731c076c230ac89d61e\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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