CVE-2026-89485 (GCVE-0-2026-89485)
Vulnerability from cvelistv5
Published
2026-09-11 19:43
Modified
2026-10-19 08:47
Severity ?
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: lockd: pin next file across nlm_inspect_file lock-drop nlm_traverse_files() pins the current file with f_count++ across a mutex_unlock for nlm_inspect_file(), but nothing pins the saved next pointer. A concurrent nlm_release_file() can kfree the next file during the unlock window, and the iterator dereferences freed memory on the next loop step. Pin both current and next before the lock-drop. Advance by swapping the pinned cursors at the end of each iteration so next is always held alive across the unlock. Always call nlm_file_release() after dropping the iteration pin, regardless of whether the file matched the predicate. Use nlm_file_inuse(), which does a live walk of the inode lock list, rather than the cached f_locks field, so skipped files that never ran nlm_inspect_file() are evaluated correctly. Because every file in a hash bucket is now pinned and released, files skipped by the is_failover_file predicate that have no locks, blocks, shares, or external references are deleted during traversal. The old code never evaluated skipped files for cleanup. The new behavior is intentional: such files are stale and should not persist in the table.
References
Impacted products
Vendor Product Version
Linux Linux Version: 01df9c5e918ae5559f2d96da0143f8bfbb9e6171
Version: 01df9c5e918ae5559f2d96da0143f8bfbb9e6171
Version: 01df9c5e918ae5559f2d96da0143f8bfbb9e6171
Version: 01df9c5e918ae5559f2d96da0143f8bfbb9e6171
Version: 01df9c5e918ae5559f2d96da0143f8bfbb9e6171
Version: 01df9c5e918ae5559f2d96da0143f8bfbb9e6171
Version: 01df9c5e918ae5559f2d96da0143f8bfbb9e6171
Version: 01df9c5e918ae5559f2d96da0143f8bfbb9e6171
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/lockd/svcsubs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "e3c413f789eaf0170275c7eba523ead73d963f30",
              "status": "affected",
              "version": "01df9c5e918ae5559f2d96da0143f8bfbb9e6171",
              "versionType": "git"
            },
            {
              "lessThan": "08a455f87b14c7ff22ae3fdadda62a796a3a5572",
              "status": "affected",
              "version": "01df9c5e918ae5559f2d96da0143f8bfbb9e6171",
              "versionType": "git"
            },
            {
              "lessThan": "550c19222c7132c888e23c9d89079ba1c9bc4cca",
              "status": "affected",
              "version": "01df9c5e918ae5559f2d96da0143f8bfbb9e6171",
              "versionType": "git"
            },
            {
              "lessThan": "350087f231c11efcd288c310707c40eab63ca583",
              "status": "affected",
              "version": "01df9c5e918ae5559f2d96da0143f8bfbb9e6171",
              "versionType": "git"
            },
            {
              "lessThan": "c24bdb7df2f34bdc38ca8a73796f5acb40f1830c",
              "status": "affected",
              "version": "01df9c5e918ae5559f2d96da0143f8bfbb9e6171",
              "versionType": "git"
            },
            {
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              "status": "affected",
              "version": "01df9c5e918ae5559f2d96da0143f8bfbb9e6171",
              "versionType": "git"
            },
            {
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              "status": "affected",
              "version": "01df9c5e918ae5559f2d96da0143f8bfbb9e6171",
              "versionType": "git"
            },
            {
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              "version": "01df9c5e918ae5559f2d96da0143f8bfbb9e6171",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/lockd/svcsubs.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.18"
            },
            {
              "lessThan": "2.6.18",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.270",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.221",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.188",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.109",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "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": "5.10.270",
                  "versionStartIncluding": "2.6.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.221",
                  "versionStartIncluding": "2.6.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.188",
                  "versionStartIncluding": "2.6.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.157",
                  "versionStartIncluding": "2.6.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.109",
                  "versionStartIncluding": "2.6.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.50",
                  "versionStartIncluding": "2.6.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.4",
                  "versionStartIncluding": "2.6.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "2.6.18",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlockd: pin next file across nlm_inspect_file lock-drop\n\nnlm_traverse_files() pins the current file with f_count++ across\na mutex_unlock for nlm_inspect_file(), but nothing pins the saved\nnext pointer.  A concurrent nlm_release_file() can kfree the next\nfile during the unlock window, and the iterator dereferences freed\nmemory on the next loop step.\n\nPin both current and next before the lock-drop.  Advance by\nswapping the pinned cursors at the end of each iteration so next\nis always held alive across the unlock.\n\nAlways call nlm_file_release() after dropping the iteration pin,\nregardless of whether the file matched the predicate.  Use\nnlm_file_inuse(), which does a live walk of the inode lock list,\nrather than the cached f_locks field, so skipped files that never\nran nlm_inspect_file() are evaluated correctly.\n\nBecause every file in a hash bucket is now pinned and released,\nfiles skipped by the is_failover_file predicate that have no\nlocks, blocks, shares, or external references are deleted during\ntraversal.  The old code never evaluated skipped files for\ncleanup.  The new behavior is intentional: such files are stale\nand should not persist in the table."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - lockd is the in-kernel NLM RPC server on TCP/UDP, reached by remote NFSv3 clients. nlm_traverse_files() runs on NLMPROC_FREE_ALL, and nlm_release_file() runs from LOCK/UNLOCK/TEST and from rpciod NLM_GRANTED_MSG completion, so the UAF is triggered by network NLM traffic.\nAC:L - A remote NFS client can populate nlm_files via LOCK, send FREE_ALL to drop nlm_file_mutex inside nlm_traverse_files(), and concurrently complete in-flight GRANTED_MSG callbacks so rpciod\u0027s nlmsvc_grant_release() calls nlm_release_file() on the unpinned next object; the attacker drives both sides of the race.\nPR:N - lockd_authenticate() accepts RPC_AUTH_NULL and RPC_AUTH_UNIX. FREE_ALL is not a privileged-port callback, and nlm_fopen() opens files with NFSD_MAY_BYPASS_GSS|NFSD_MAY_NLM, so no host account or capability is required.\nUI:N - Exploitation uses only attacker-sent NLM RPCs (LOCK/FREE_ALL and grant-callback completion); no victim user or administrator action is required.\nS:U - The use-after-free is in the host kernel\u0027s lockd file table and impacts that same kernel; it does not cross a VM, IOMMU, or other security-authority boundary.\nC:H - The iterator dereferences a kfree\u0027d struct nlm_file (list pointers, f_file[], f_count). This UAF lets an attacker reuse the slab object and obtain a kernel read primitive, so confidentiality impact is high.\nI:H - The same nlm_file UAF is a kernel heap free of list nodes, mutex state, and struct file pointers, which can be sprayed for an arbitrary write and control-flow hijack, so integrity impact is high.\nA:H - Walking the freed nlm_file in nlm_traverse_files() causes a kernel oops/panic (KASAN slab-use-after-free), so availability impact is high."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:47:35.868Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/e3c413f789eaf0170275c7eba523ead73d963f30"
        },
        {
          "url": "https://git.kernel.org/stable/c/08a455f87b14c7ff22ae3fdadda62a796a3a5572"
        },
        {
          "url": "https://git.kernel.org/stable/c/550c19222c7132c888e23c9d89079ba1c9bc4cca"
        },
        {
          "url": "https://git.kernel.org/stable/c/350087f231c11efcd288c310707c40eab63ca583"
        },
        {
          "url": "https://git.kernel.org/stable/c/c24bdb7df2f34bdc38ca8a73796f5acb40f1830c"
        },
        {
          "url": "https://git.kernel.org/stable/c/41f0a6d31615fcae261bf28a0aa50050dc93a401"
        },
        {
          "url": "https://git.kernel.org/stable/c/e999a88133654c6dfc68487fb49da5f20dfa2d4f"
        },
        {
          "url": "https://git.kernel.org/stable/c/526c49cff3f72c3ec74752016380c7567040581b"
        }
      ],
      "title": "lockd: pin next file across nlm_inspect_file lock-drop",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89485",
    "datePublished": "2026-09-11T19:43:39.403Z",
    "dateReserved": "2026-09-11T19:38:34.712Z",
    "dateUpdated": "2026-10-19T08:47:35.868Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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