CVE-2026-89644 (GCVE-0-2026-89644)
Vulnerability from cvelistv5
Published
2026-09-11 19:45
Modified
2026-10-21 12:48
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: btrfs: fix extent map leak in NOCOW direct I/O write btrfs_dio_iomap_begin() calls btrfs_get_extent(), which returns an extent map reference that must be dropped on all exit paths. For direct writes into a NOCOW range, btrfs_get_blocks_direct_write() keeps using that extent map and asks btrfs_create_dio_extent() to allocate the ordered extent. If that fails, for example because btrfs_alloc_ordered_extent() fails, the function returns the error without dropping the input extent map. The PREALLOC path avoided this by dropping the input extent map before replacing it with the newly created one. Check the error from btrfs_create_dio_extent() before replacing the map and drop the input extent map on failure.
References
Impacted products
Vendor Product Version
Linux Linux Version: 5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af
Version: 5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af
Version: 5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af
Version: 5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af
Version: 5f9a8a51d8b95505d8de8b7191ae2ed8c504d4af
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{
  "containers": {
    "cna": {
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/btrfs/direct-io.c"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
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              "version": "4.7"
            },
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              "version": "0",
              "versionType": "semver"
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              "versionType": "semver"
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              "versionType": "semver"
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              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.160",
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                  "vulnerable": true
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              ],
              "negate": false,
              "operator": "OR"
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          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix extent map leak in NOCOW direct I/O write\n\nbtrfs_dio_iomap_begin() calls btrfs_get_extent(), which returns an\nextent map reference that must be dropped on all exit paths.\n\nFor direct writes into a NOCOW range, btrfs_get_blocks_direct_write()\nkeeps using that extent map and asks btrfs_create_dio_extent() to\nallocate the ordered extent. If that fails, for example because\nbtrfs_alloc_ordered_extent() fails, the function returns the error\nwithout dropping the input extent map. The PREALLOC path avoided this by\ndropping the input extent map before replacing it with the newly created\none.\n\nCheck the error from btrfs_create_dio_extent() before replacing the\nmap and drop the input extent map on failure."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:48:08.939Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/cb732d302245b14943a5017015fffa8e6db7a6c0"
        },
        {
          "url": "https://git.kernel.org/stable/c/b7c873765875645b11503f94c9bae2ca80127375"
        },
        {
          "url": "https://git.kernel.org/stable/c/f42efd634c0ae7ba0ce2fc5e30e291b0803b0ae2"
        },
        {
          "url": "https://git.kernel.org/stable/c/05a1a816eef8b3e4332620a64fc8cf45c4eb5c0d"
        },
        {
          "url": "https://git.kernel.org/stable/c/3f950867c307c5413d628a153ac44915bd117ffd"
        }
      ],
      "title": "btrfs: fix extent map leak in NOCOW direct I/O write",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89644",
    "datePublished": "2026-09-11T19:45:36.268Z",
    "dateReserved": "2026-09-11T19:38:34.741Z",
    "dateUpdated": "2026-10-21T12:48:08.939Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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