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HighFix available

nfsd: provide locking for v4_end_grace

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: nfsd: provide locking for v4_end_grace Writing to v4_end_grace can race with server shutdown and result in memory being accessed after it was freed - reclaim_str_hashtbl in particularly. We cannot hold nfsd_mutex across the nfsd4_end_grace() call as that is held while client_tracking_op->init() is called and that can wait for an upcall to nfsdcltrack which can write to v4_end_grace, resulting in a deadlock. nfsd4_end_grace() is also called by the landromat work queue and this doesn't require locking as server shutdown will stop the work and wait for it before freeing anything that nfsd4_end_grace() might access. However, we must be sure that writing to v4_end_grace doesn't restart the work item after shutdown has already waited for it. For this we add a new flag protected with nn->client_lock. It is set only while it is safe to make client tracking calls, and v4_end_grace only schedules work while the flag is set with the spinlock held. So this patch adds a nfsd_net field "client_tracking_active" which is set as described. Another field "grace_end_forced", is set when v4_end_grace is written. After this is set, and providing client_tracking_active is set, the laundromat is scheduled. This "grace_end_forced" field bypasses other checks for whether the grace period has finished. This resolves a race which can result in use-after-free.

Products
Kernel
Affected versions
Not specified
Fixed versions
5.10.248, 5.15.198, 6.1.161, 6.12.66, 6.18.6, 6.6.121
CVEs
CVE-2026-22980
Confirmed fixed CVEs
Not specified
Updated in this feed
5 Nov 2026, 06:11 UTC · Revision 1

Source evidence

nfsd: provide locking for v4_end_grace

core-osv · Original source

Published 23 Jan 2026, 15:24 UTC

In the Linux kernel, the following vulnerability has been resolved: nfsd: provide locking for v4_end_grace Writing to v4_end_grace can race with server shutdown and result in memory being accessed after it was freed - reclaim_str_hashtbl in particularly. We cannot hold nfsd_mutex across the nfsd4_end_grace() call as that is held while client_tracking_op->init() is called and that can wait for an upcall to nfsdcltrack which can write to v4_end_grace, resulting in a deadlock. nfsd4_end_grace() is also called by the landromat work queue and this doesn't require locking as server shutdown will stop the work and wait for it before freeing anything that nfsd4_end_grace() might access. However, we must be sure that writing to v4_end_grace doesn't restart the work item after shutdown has already waited for it. For this we add a new flag protected with nn->client_lock. It is set only while it is safe to make client tracking calls, and v4_end_grace only schedules work while the flag is set with the spinlock held. So this patch adds a nfsd_net field "client_tracking_active" which is set as described. Another field "grace_end_forced", is set when v4_end_grace is written. After this is set, and providing client_tracking_active is set, the laundromat is scheduled. This "grace_end_forced" field bypasses other checks for whether the grace period has finished. This resolves a race which can result in use-after-free.

osv:CVE-2026-22980

Kernel

Fixed versions: 5.10.248, 5.15.198, 6.1.161, 6.6.121, 6.12.66, 6.18.6

Complete source record
{
  "id": "342b8ba8247700924631fbd5444d0764dd41c5adbbda51ab15ab7482e22c7ea0",
  "url": "https://osv.dev/vulnerability/CVE-2026-22980",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "nfsd: provide locking for v4_end_grace",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: nfsd: provide locking for v4_end_grace Writing to v4_end_grace can race with server shutdown and result in memory being accessed after it was freed - reclaim_str_hashtbl in particularly. We cannot hold nfsd_mutex across the nfsd4_end_grace() call as that is held while client_tracking_op->init() is called and that can wait for an upcall to nfsdcltrack which can write to v4_end_grace, resulting in a deadlock. nfsd4_end_grace() is also called by the landromat work queue and this doesn't require locking as server shutdown will stop the work and wait for it before freeing anything that nfsd4_end_grace() might access. However, we must be sure that writing to v4_end_grace doesn't restart the work item after shutdown has already waited for it. For this we add a new flag protected with nn->client_lock. It is set only while it is safe to make client tracking calls, and v4_end_grace only schedules work while the flag is set with the spinlock held. So this patch adds a nfsd_net field \"client_tracking_active\" which is set as described. Another field \"grace_end_forced\", is set when v4_end_grace is written. After this is set, and providing client_tracking_active is set, the laundromat is scheduled. This \"grace_end_forced\" field bypasses other checks for whether the grace period has finished. This resolves a race which can result in use-after-free.",
    "evidence": "osv:CVE-2026-22980",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.10.248",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.15.198",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.1.161",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.6.121",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.12.66",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.18.6",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-22980",
      "aliases": [
        "CVE-2026-22980"
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      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
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              "events": [
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        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "3.18.0"
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                {
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              ]
            },
            {
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                  "introduced": "5.11.0"
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            {
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      ],
      "modified": "2026-10-28T02:30:42.959472891Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-019113.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-457936.html",
        "https://git.kernel.org/stable/c/06600719d0f7a723811c45e4d51f5b742f345309",
        "https://git.kernel.org/stable/c/2857bd59feb63fcf40fe4baf55401baea6b4feb4",
        "https://git.kernel.org/stable/c/34eb22836e0cdba093baac66599d68c4cd245a9d",
        "https://git.kernel.org/stable/c/53f07d095e7e680c5e4569a55a019f2c0348cdc6",
        "https://git.kernel.org/stable/c/ba4811c8b433bfa681729ca42cc62b6034f223b0",
        "https://git.kernel.org/stable/c/ca97360860eb02e3ae4ba42c19b439a0fcecbf06",
        "https://git.kernel.org/stable/c/e8bfa2401d4c51eca6e48e9b33c798828ca9df61",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/22xxx/CVE-2026-22980.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-22980",
        "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/2026/22xxx/CVE-2026-22980.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-22980",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 511002,
  "published_at": "2026-01-23T15:24:02.924+00:00"
}