CVE-2026-22980 (GCVE-0-2026-22980)

Vulnerability from cvelistv5 – Published: 2026-01-23 15:24 – Updated: 2026-01-23 15:24
VLAI?
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.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 , < ca97360860eb02e3ae4ba42c19b439a0fcecbf06 (git)
Affected: 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 , < e8bfa2401d4c51eca6e48e9b33c798828ca9df61 (git)
Affected: 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 , < 34eb22836e0cdba093baac66599d68c4cd245a9d (git)
Affected: 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 , < 06600719d0f7a723811c45e4d51f5b742f345309 (git)
Affected: 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 , < ba4811c8b433bfa681729ca42cc62b6034f223b0 (git)
Affected: 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 , < 53f07d095e7e680c5e4569a55a019f2c0348cdc6 (git)
Affected: 7f5ef2e900d9462bf9cffaf6bb246ed87a20a6d6 , < 2857bd59feb63fcf40fe4baf55401baea6b4feb4 (git)
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    Linux Linux Affected: 3.18
Unaffected: 0 , < 3.18 (semver)
Unaffected: 5.10.248 , ≤ 5.10.* (semver)
Unaffected: 5.15.198 , ≤ 5.15.* (semver)
Unaffected: 6.1.161 , ≤ 6.1.* (semver)
Unaffected: 6.6.121 , ≤ 6.6.* (semver)
Unaffected: 6.12.66 , ≤ 6.12.* (semver)
Unaffected: 6.18.6 , ≤ 6.18.* (semver)
Unaffected: 6.19-rc5 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/netns.h",
            "fs/nfsd/nfs4state.c",
            "fs/nfsd/nfsctl.c",
            "fs/nfsd/state.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "versionType": "git"
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              "status": "affected",
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              "versionType": "git"
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        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/netns.h",
            "fs/nfsd/nfs4state.c",
            "fs/nfsd/nfsctl.c",
            "fs/nfsd/state.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.18"
            },
            {
              "lessThan": "3.18",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.248",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.198",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.161",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.121",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.66",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.19-rc5",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.10.248",
                  "versionStartIncluding": "3.18",
                  "vulnerable": true
                },
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                  "vulnerable": true
                },
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                {
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                  "versionEndExcluding": "6.6.121",
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                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                },
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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\nnfsd: provide locking for v4_end_grace\n\nWriting to v4_end_grace can race with server shutdown and result in\nmemory being accessed after it was freed - reclaim_str_hashtbl in\nparticularly.\n\nWe cannot hold nfsd_mutex across the nfsd4_end_grace() call as that is\nheld while client_tracking_op-\u003einit() is called and that can wait for\nan upcall to nfsdcltrack which can write to v4_end_grace, resulting in a\ndeadlock.\n\nnfsd4_end_grace() is also called by the landromat work queue and this\ndoesn\u0027t require locking as server shutdown will stop the work and wait\nfor it before freeing anything that nfsd4_end_grace() might access.\n\nHowever, we must be sure that writing to v4_end_grace doesn\u0027t restart\nthe work item after shutdown has already waited for it.  For this we\nadd a new flag protected with nn-\u003eclient_lock.  It is set only while it\nis safe to make client tracking calls, and v4_end_grace only schedules\nwork while the flag is set with the spinlock held.\n\nSo this patch adds a nfsd_net field \"client_tracking_active\" which is\nset as described.  Another field \"grace_end_forced\", is set when\nv4_end_grace is written.  After this is set, and providing\nclient_tracking_active is set, the laundromat is scheduled.\nThis \"grace_end_forced\" field bypasses other checks for whether the\ngrace period has finished.\n\nThis resolves a race which can result in use-after-free."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-01-23T15:24:02.924Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/ca97360860eb02e3ae4ba42c19b439a0fcecbf06"
        },
        {
          "url": "https://git.kernel.org/stable/c/e8bfa2401d4c51eca6e48e9b33c798828ca9df61"
        },
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          "url": "https://git.kernel.org/stable/c/34eb22836e0cdba093baac66599d68c4cd245a9d"
        },
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          "url": "https://git.kernel.org/stable/c/06600719d0f7a723811c45e4d51f5b742f345309"
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        {
          "url": "https://git.kernel.org/stable/c/53f07d095e7e680c5e4569a55a019f2c0348cdc6"
        },
        {
          "url": "https://git.kernel.org/stable/c/2857bd59feb63fcf40fe4baf55401baea6b4feb4"
        }
      ],
      "title": "nfsd: provide locking for v4_end_grace",
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  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-22980",
    "datePublished": "2026-01-23T15:24:02.924Z",
    "dateReserved": "2026-01-13T15:37:45.936Z",
    "dateUpdated": "2026-01-23T15:24:02.924Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-22980\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-01-23T16:15:54.003\",\"lastModified\":\"2026-01-26T15:03:51.687\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nnfsd: provide locking for v4_end_grace\\n\\nWriting to v4_end_grace can race with server shutdown and result in\\nmemory being accessed after it was freed - reclaim_str_hashtbl in\\nparticularly.\\n\\nWe cannot hold nfsd_mutex across the nfsd4_end_grace() call as that is\\nheld while client_tracking_op-\u003einit() is called and that can wait for\\nan upcall to nfsdcltrack which can write to v4_end_grace, resulting in a\\ndeadlock.\\n\\nnfsd4_end_grace() is also called by the landromat work queue and this\\ndoesn\u0027t require locking as server shutdown will stop the work and wait\\nfor it before freeing anything that nfsd4_end_grace() might access.\\n\\nHowever, we must be sure that writing to v4_end_grace doesn\u0027t restart\\nthe work item after shutdown has already waited for it.  For this we\\nadd a new flag protected with nn-\u003eclient_lock.  It is set only while it\\nis safe to make client tracking calls, and v4_end_grace only schedules\\nwork while the flag is set with the spinlock held.\\n\\nSo this patch adds a nfsd_net field \\\"client_tracking_active\\\" which is\\nset as described.  Another field \\\"grace_end_forced\\\", is set when\\nv4_end_grace is written.  After this is set, and providing\\nclient_tracking_active is set, the laundromat is scheduled.\\nThis \\\"grace_end_forced\\\" field bypasses other checks for whether the\\ngrace period has finished.\\n\\nThis resolves a race which can result in use-after-free.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/06600719d0f7a723811c45e4d51f5b742f345309\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/2857bd59feb63fcf40fe4baf55401baea6b4feb4\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/34eb22836e0cdba093baac66599d68c4cd245a9d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/53f07d095e7e680c5e4569a55a019f2c0348cdc6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ba4811c8b433bfa681729ca42cc62b6034f223b0\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ca97360860eb02e3ae4ba42c19b439a0fcecbf06\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e8bfa2401d4c51eca6e48e9b33c798828ca9df61\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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