CVE-2026-93212 (GCVE-0-2026-93212)

Vulnerability from cvelistv5 – Published: 2026-09-24 15:10 – Updated: 2026-10-19 09:07
VLAI
Title
nfsd: guard nfsd_serv deref in nfsd_file_net_dispose
Summary
In the Linux kernel, the following vulnerability has been resolved: nfsd: guard nfsd_serv deref in nfsd_file_net_dispose nfsd_file_net_dispose() is the consumer side of l->freeme: the nfsd service thread loop calls it to drain entries that the filecache garbage collector and shrinker append via nfsd_file_dispose_list_delayed(). During per-net teardown, nn->nfsd_serv is cleared before the filecache laundrette is shut down, so the service thread can still run a dispose pass that finds more than eight entries on l->freeme and dereferences a NULL svc_serv: nfsd service thread loop nfsd_file_net_dispose(nn) if (!list_empty(&l->freeme)) { ... svc_wake_up(nn->nfsd_serv); /* nn->nfsd_serv == NULL */ } The sibling helper nfsd_file_dispose_list_delayed() already documents this ordering and caches nn->nfsd_serv into a local before testing it for NULL. nfsd_file_net_dispose() was introduced with the same raw svc_wake_up(nn->nfsd_serv) call and never picked up the guard. Fix by loading nn->nfsd_serv into a local svc_serv pointer and only calling svc_wake_up() when it is non-NULL, matching the pattern in nfsd_file_dispose_list_delayed().
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6641 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: ffb402596147ac583f3464ff5c48feb9423e3838 , < f4776c1c4b38fbc459420321c8ece87d0f7f95fb (git)
Affected: ffb402596147ac583f3464ff5c48feb9423e3838 , < 59baf45a06435194005fc5fa9a42d89f77a30432 (git)
Affected: ffb402596147ac583f3464ff5c48feb9423e3838 , < 766170b4fd2daaf5c4d6735560101474e18edab6 (git)
Affected: ffb402596147ac583f3464ff5c48feb9423e3838 , < 9f1ddfc8cb9076592401a611eb3a44d36186d014 (git)
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Linux Linux Affected: 6.9
Unaffected: 0 , < 6.9 (semver)
Unaffected: 6.12.109 , ≤ 6.12.* (semver)
Unaffected: 6.18.50 , ≤ 6.18.* (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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          "programFiles": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: guard nfsd_serv deref in nfsd_file_net_dispose\n\nnfsd_file_net_dispose() is the consumer side of l-\u003efreeme: the nfsd\nservice thread loop calls it to drain entries that the filecache\ngarbage collector and shrinker append via\nnfsd_file_dispose_list_delayed().  During per-net teardown,\nnn-\u003enfsd_serv is cleared before the filecache laundrette is shut\ndown, so the service thread can still run a dispose pass that finds\nmore than eight entries on l-\u003efreeme and dereferences a NULL\nsvc_serv:\n\n    nfsd service thread loop\n      nfsd_file_net_dispose(nn)\n        if (!list_empty(\u0026l-\u003efreeme)) {\n            ...\n            svc_wake_up(nn-\u003enfsd_serv);   /* nn-\u003enfsd_serv == NULL */\n        }\n\nThe sibling helper nfsd_file_dispose_list_delayed() already documents\nthis ordering and caches nn-\u003enfsd_serv into a local before testing it\nfor NULL.  nfsd_file_net_dispose() was introduced with the same raw\nsvc_wake_up(nn-\u003enfsd_serv) call and never picked up the guard.\n\nFix by loading nn-\u003enfsd_serv into a local svc_serv pointer and only\ncalling svc_wake_up() when it is non-NULL, matching the pattern in\nnfsd_file_dispose_list_delayed()."
        }
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        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/9f1ddfc8cb9076592401a611eb3a44d36186d014"
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      "title": "nfsd: guard nfsd_serv deref in nfsd_file_net_dispose",
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    "datePublished": "2026-09-24T15:10:35.280Z",
    "dateReserved": "2026-09-17T16:02:15.093Z",
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: guard nfsd_serv deref in nfsd_file_net_dispose\n\nnfsd_file_net_dispose() is the consumer side of l-\u003efreeme: the nfsd\nservice thread loop calls it to drain entries that the filecache\ngarbage collector and shrinker append via\nnfsd_file_dispose_list_delayed().  During per-net teardown,\nnn-\u003enfsd_serv is cleared before the filecache laundrette is shut\ndown, so the service thread can still run a dispose pass that finds\nmore than eight entries on l-\u003efreeme and dereferences a NULL\nsvc_serv:\n\n    nfsd service thread loop\n      nfsd_file_net_dispose(nn)\n        if (!list_empty(\u0026l-\u003efreeme)) {\n            ...\n            svc_wake_up(nn-\u003enfsd_serv);   /* nn-\u003enfsd_serv == NULL */\n        }\n\nThe sibling helper nfsd_file_dispose_list_delayed() already documents\nthis ordering and caches nn-\u003enfsd_serv into a local before testing it\nfor NULL.  nfsd_file_net_dispose() was introduced with the same raw\nsvc_wake_up(nn-\u003enfsd_serv) call and never picked up the guard.\n\nFix by loading nn-\u003enfsd_serv into a local svc_serv pointer and only\ncalling svc_wake_up() when it is non-NULL, matching the pattern in\nnfsd_file_dispose_list_delayed()."
          }
        ],
        "id": "CVE-2026-93212",
        "lastModified": "2026-10-19T10:17:12.113",
        "metrics": {},
        "published": "2026-09-24T16:17:16.133",
        "references": [
          {
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      "cve": "CVE-2026-93212",
      "id": "CVE-2026-93212",
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      "product_status:known_affected": "110",
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      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: nfsd: guard nfsd_serv deref in nfsd_file_net_dispose",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-93212.json",
      "version": "3"
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  }
}



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