FKIE_CVE-2026-93212

Vulnerability from fkie_nvd - Published: 2026-09-24 16:17 - Updated: 2026-09-24 16:17
Severity
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().
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/59baf45a06435194005fc5fa9a42d89f77a30432
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/766170b4fd2daaf5c4d6735560101474e18edab6
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/9f1ddfc8cb9076592401a611eb3a44d36186d014
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f4776c1c4b38fbc459420321c8ece87d0f7f95fb
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/filecache.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f4776c1c4b38fbc459420321c8ece87d0f7f95fb",
              "status": "affected",
              "version": "ffb402596147ac583f3464ff5c48feb9423e3838",
              "versionType": "git"
            },
            {
              "lessThan": "59baf45a06435194005fc5fa9a42d89f77a30432",
              "status": "affected",
              "version": "ffb402596147ac583f3464ff5c48feb9423e3838",
              "versionType": "git"
            },
            {
              "lessThan": "766170b4fd2daaf5c4d6735560101474e18edab6",
              "status": "affected",
              "version": "ffb402596147ac583f3464ff5c48feb9423e3838",
              "versionType": "git"
            },
            {
              "lessThan": "9f1ddfc8cb9076592401a611eb3a44d36186d014",
              "status": "affected",
              "version": "ffb402596147ac583f3464ff5c48feb9423e3838",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/nfsd/filecache.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.9"
            },
            {
              "lessThan": "6.9",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.109",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.50",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "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": "2026-09-24T16:17:16.133",
  "metrics": {},
  "published": "2026-09-24T16:17:16.133",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/59baf45a06435194005fc5fa9a42d89f77a30432"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/766170b4fd2daaf5c4d6735560101474e18edab6"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/9f1ddfc8cb9076592401a611eb3a44d36186d014"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/f4776c1c4b38fbc459420321c8ece87d0f7f95fb"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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