nfsd: clear CALLBACK_RUNNING on failed delegation recall queue

{
  "id": "808267c7cfa2ab0a01d006362221e85d6271b7dfa07e9c56d0e8c4a649be574c",
  "url": "https://osv.dev/vulnerability/CVE-2026-89692",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "nfsd: clear CALLBACK_RUNNING on failed delegation recall queue",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: nfsd: clear CALLBACK_RUNNING on failed delegation recall queue nfsd_break_one_deleg() sets NFSD4_CALLBACK_RUNNING via test_and_set_bit at entry to serialize recall work, then calls nfsd4_run_cb() to queue the recall. When the queue attempt fails the refcount bump is undone, but the RUNNING bit is left set. The only site that clears the bit is nfsd41_destroy_cb() (fs/nfsd/nfs4callback.c), which runs from the workqueue and is therefore unreachable when nothing was queued. The bit becomes a permanent latch on dp->dl_recall.cb_flags: every subsequent break_lease() on the same delegation hits the early-return guard in nfsd_break_one_deleg() and silently skips the recall, so the delegation is never broken and the conflicting open or lock stalls. Fix by clearing NFSD4_CALLBACK_RUNNING on the !queued branch alongside the refcount_dec.",
    "evidence": "osv:CVE-2026-89692",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.18.50",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "7.2.4",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-89692",
      "aliases": [
        "CVE-2026-89692"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
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              "type": "GIT",
              "events": [
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                {
                  "fixed": "b137930ee52e3ef38915a3511d4c070463b63a32"
                },
                {
                  "fixed": "cb2d0c4d1b3d301d042ed61365eaa8cb0141a254"
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                {
                  "fixed": "b036727d334b1b7cd4c1f1fba3b59ba93a6bbe96"
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          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89692.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.15.0"
                },
                {
                  "fixed": "6.18.50"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.19.0"
                },
                {
                  "fixed": "7.2.4"
                }
              ]
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          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-89692.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:34.511669886Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/b036727d334b1b7cd4c1f1fba3b59ba93a6bbe96",
        "https://git.kernel.org/stable/c/b137930ee52e3ef38915a3511d4c070463b63a32",
        "https://git.kernel.org/stable/c/cb2d0c4d1b3d301d042ed61365eaa8cb0141a254",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89692.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-89692",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/89xxx/CVE-2026-89692.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-89692",
        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 501998,
  "published_at": "2026-09-11T19:46:12.04+00:00"
}