{
  "schemaVersion": 1,
  "attribution": [
    {
      "source": "CISA Known Exploited Vulnerabilities",
      "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog",
      "licence": "US government work"
    },
    {
      "source": "GitHub Advisory Database",
      "url": "https://github.com/advisories",
      "licence": "CC BY 4.0"
    },
    {
      "source": "Have I Been Pwned",
      "url": "https://haveibeenpwned.com/",
      "licence": "CC BY 4.0"
    },
    {
      "source": "CVE Program (CVE records)",
      "url": "https://www.cve.org/Legal/TermsOfUse",
      "licence": "CVE Terms of Use",
      "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.",
      "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy."
    },
    {
      "source": "FIRST EPSS",
      "url": "https://www.first.org/epss/",
      "licence": "free to use; FIRST requests attribution"
    }
  ],
  "record": {
    "id": "CVE-2025-21664",
    "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2025-21664",
    "idYear": 2025,
    "status": "PUBLISHED",
    "publishedAt": "2025-01-21T12:18:19.015Z",
    "updatedAt": "2026-10-15T21:51:52.113Z",
    "importedAt": "2026-10-24T01:57:29.455Z",
    "snapshot": {
      "id": "cve_2026-10-24_midnight_baseline",
      "at": "2026-10-24T00:00:00.000Z",
      "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z"
    },
    "facts": {
      "title": "dm thin: make get_first_thin use rcu-safe list first function",
      "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\ndm thin: make get_first_thin use rcu-safe list first function\n\nThe documentation in rculist.h explains the absence of list_empty_rcu()\nand cautions programmers against relying on a list_empty() ->\nlist_first() sequence in RCU safe code.  This is because each of these\nfunctions performs its own READ_ONCE() of the list head.  This can lead\nto a situation where the list_empty() sees a valid list entry, but the\nsubsequent list_first() sees a different view of list head state after a\nmodification.\n\nIn the case of dm-thin, this author had a production box crash from a GP\nfault in the process_deferred_bios path.  This function saw a valid list\nhead in get_first_thin() but when it subsequently dereferenced that and\nturned it into a thin_c, it got the inside of the struct pool, since the\nlist was now empty and referring to itself.  The kernel on which this\noccurred printed both a warning about a refcount_t being saturated, and\na UBSAN error for an out-of-bounds cpuid access in the queued spinlock,\nprior to the fault itself.  When the resulting kdump was examined, it\nwas possible to see another thread patiently waiting in thin_dtr's\nsynchronize_rcu.\n\nThe thin_dtr call managed to pull the thin_c out of the active thins\nlist (and have it be the last entry in the active_thins list) at just\nthe wrong moment which lead to this crash.\n\nFortunately, the fix here is straight forward.  Switch get_first_thin()\nfunction to use list_first_or_null_rcu() which performs just a single\nREAD_ONCE() and returns NULL if the list is already empty.\n\nThis was run against the devicemapper test suite's thin-provisioning\nsuites for delete and suspend and no regressions were observed.",
      "affected": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "versions": [
            {
              "version": "b10ebd34cccae1b431caf1be54919aede2be7cbe",
              "status": "affected",
              "versionType": "git",
              "lessThan": "ec037fe8c0d0f6140e3d8a49c7b29cb5582160b8"
            },
            {
              "version": "b10ebd34cccae1b431caf1be54919aede2be7cbe",
              "status": "affected",
              "versionType": "git",
              "lessThan": "cd30a3960433ec2db94b3689752fa3c5df44d649"
            },
            {
              "version": "b10ebd34cccae1b431caf1be54919aede2be7cbe",
              "status": "affected",
              "versionType": "git",
              "lessThan": "802666a40c71a23542c43a3f87e3a2d0f4e8fe45"
            },
            {
              "version": "b10ebd34cccae1b431caf1be54919aede2be7cbe",
              "status": "affected",
              "versionType": "git",
              "lessThan": "12771050b6d059eea096993bf2001da9da9fddff"
            },
            {
              "version": "b10ebd34cccae1b431caf1be54919aede2be7cbe",
              "status": "affected",
              "versionType": "git",
              "lessThan": "6b305e98de0d225ccebfb225730a9f560d28ecb0"
            },
            {
              "version": "b10ebd34cccae1b431caf1be54919aede2be7cbe",
              "status": "affected",
              "versionType": "git",
              "lessThan": "cbd0d5ecfa390ac29c5380200147d09c381b2ac6"
            },
            {
              "version": "b10ebd34cccae1b431caf1be54919aede2be7cbe",
              "status": "affected",
              "versionType": "git",
              "lessThan": "80f130bfad1dab93b95683fc39b87235682b8f72"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "versions": [
            {
              "version": "3.15",
              "status": "affected"
            },
            {
              "version": "0",
              "status": "unaffected",
              "versionType": "semver",
              "lessThan": "3.15"
            },
            {
              "version": "5.4.290",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.4.*"
            },
            {
              "version": "5.10.234",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.10.*"
            },
            {
              "version": "5.15.177",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "5.15.*"
            },
            {
              "version": "6.1.125",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.1.*"
            },
            {
              "version": "6.6.72",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "version": "6.12.10",
              "status": "unaffected",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "version": "6.13",
              "status": "unaffected",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ]
        }
      ]
    }
  }
}