NFSv4: Fix a deadlock when recovering state on a sillyrenamed file

{
  "id": "e17edcaf0b870f8350ab9f823209dfdfb9ed1a8099f8b73cbc801a0fb1f68e4f",
  "url": "https://osv.dev/vulnerability/CVE-2025-21900",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "NFSv4: Fix a deadlock when recovering state on a sillyrenamed file",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: NFSv4: Fix a deadlock when recovering state on a sillyrenamed file If the file is sillyrenamed, and slated for delete on close, it is possible for a server reboot to triggeer an open reclaim, with can again race with the application call to close(). When that happens, the call to put_nfs_open_context() can trigger a synchronous delegreturn call which deadlocks because it is not marked as privileged. Instead, ensure that the call to nfs4_inode_return_delegation_on_close() catches the delegreturn, and schedules it asynchronously.",
    "evidence": "osv:CVE-2025-21900",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.12.18",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.13.6",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2025-21900",
      "aliases": [
        "CVE-2025-21900"
      ],
      "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": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "adb4b42d19aea91826621a8d0bac94cf2c08f8bc"
                },
                {
                  "fixed": "4fe4ae6c2e01d028856b73b6328b12b8945df871"
                },
                {
                  "fixed": "f41a60bc43e7abbc636fee78bed0d74c31e738b0"
                },
                {
                  "fixed": "8f8df955f078e1a023ee55161935000a67651f38"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-21900.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.11.0"
                },
                {
                  "fixed": "6.12.18"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "6.13.0"
                },
                {
                  "fixed": "6.13.6"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-21900.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:49.599842272Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/4fe4ae6c2e01d028856b73b6328b12b8945df871",
        "https://git.kernel.org/stable/c/8f8df955f078e1a023ee55161935000a67651f38",
        "https://git.kernel.org/stable/c/f41a60bc43e7abbc636fee78bed0d74c31e738b0",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21900.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-21900",
        "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/2025/21xxx/CVE-2025-21900.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2025-21900",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 517756,
  "published_at": "2025-04-01T15:26:51.29+00:00"
}