CVE-2025-68292 (GCVE-0-2025-68292)
Vulnerability from cvelistv5
Published
2025-12-16 15:06
Modified
2025-12-16 15:06
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: mm/memfd: fix information leak in hugetlb folios When allocating hugetlb folios for memfd, three initialization steps are missing: 1. Folios are not zeroed, leading to kernel memory disclosure to userspace 2. Folios are not marked uptodate before adding to page cache 3. hugetlb_fault_mutex is not taken before hugetlb_add_to_page_cache() The memfd allocation path bypasses the normal page fault handler (hugetlb_no_page) which would handle all of these initialization steps. This is problematic especially for udmabuf use cases where folios are pinned and directly accessed by userspace via DMA. Fix by matching the initialization pattern used in hugetlb_no_page(): - Zero the folio using folio_zero_user() which is optimized for huge pages - Mark it uptodate with folio_mark_uptodate() - Take hugetlb_fault_mutex before adding to page cache to prevent races The folio_zero_user() change also fixes a potential security issue where uninitialized kernel memory could be disclosed to userspace through read() or mmap() operations on the memfd.
References
Impacted products
Vendor Product Version
Linux Linux Version: 89c1905d9c140372b7f50ef48f42378cf85d9bc5
Version: 89c1905d9c140372b7f50ef48f42378cf85d9bc5
Version: 89c1905d9c140372b7f50ef48f42378cf85d9bc5
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{
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          "product": "Linux",
          "programFiles": [
            "mm/memfd.c"
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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/memfd: fix information leak in hugetlb folios\n\nWhen allocating hugetlb folios for memfd, three initialization steps are\nmissing:\n\n1. Folios are not zeroed, leading to kernel memory disclosure to userspace\n2. Folios are not marked uptodate before adding to page cache\n3. hugetlb_fault_mutex is not taken before hugetlb_add_to_page_cache()\n\nThe memfd allocation path bypasses the normal page fault handler\n(hugetlb_no_page) which would handle all of these initialization steps. \nThis is problematic especially for udmabuf use cases where folios are\npinned and directly accessed by userspace via DMA.\n\nFix by matching the initialization pattern used in hugetlb_no_page():\n- Zero the folio using folio_zero_user() which is optimized for huge pages\n- Mark it uptodate with folio_mark_uptodate()\n- Take hugetlb_fault_mutex before adding to page cache to prevent races\n\nThe folio_zero_user() change also fixes a potential security issue where\nuninitialized kernel memory could be disclosed to userspace through read()\nor mmap() operations on the memfd."
        }
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      "providerMetadata": {
        "dateUpdated": "2025-12-16T15:06:12.772Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/50b4c1c28733a536d637d2f0401d60bcfef60ef2"
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        {
          "url": "https://git.kernel.org/stable/c/de8798965fd0d9a6c47fc2ac57767ec32de12b49"
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      ],
      "title": "mm/memfd: fix information leak in hugetlb folios",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2025-68292",
    "datePublished": "2025-12-16T15:06:12.772Z",
    "dateReserved": "2025-12-16T14:48:05.292Z",
    "dateUpdated": "2025-12-16T15:06:12.772Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-68292\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-12-16T16:16:08.087\",\"lastModified\":\"2025-12-18T15:08:06.237\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nmm/memfd: fix information leak in hugetlb folios\\n\\nWhen allocating hugetlb folios for memfd, three initialization steps are\\nmissing:\\n\\n1. Folios are not zeroed, leading to kernel memory disclosure to userspace\\n2. Folios are not marked uptodate before adding to page cache\\n3. hugetlb_fault_mutex is not taken before hugetlb_add_to_page_cache()\\n\\nThe memfd allocation path bypasses the normal page fault handler\\n(hugetlb_no_page) which would handle all of these initialization steps. \\nThis is problematic especially for udmabuf use cases where folios are\\npinned and directly accessed by userspace via DMA.\\n\\nFix by matching the initialization pattern used in hugetlb_no_page():\\n- Zero the folio using folio_zero_user() which is optimized for huge pages\\n- Mark it uptodate with folio_mark_uptodate()\\n- Take hugetlb_fault_mutex before adding to page cache to prevent races\\n\\nThe folio_zero_user() change also fixes a potential security issue where\\nuninitialized kernel memory could be disclosed to userspace through read()\\nor mmap() operations on the memfd.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/50b4c1c28733a536d637d2f0401d60bcfef60ef2\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b09d7c4dc642849d9a96753233c6d00364017fd6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/de8798965fd0d9a6c47fc2ac57767ec32de12b49\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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