fkie_cve-2021-47506
Vulnerability from fkie_nvd
Published
2024-05-24 15:15
Modified
2025-01-06 20:44
Summary
In the Linux kernel, the following vulnerability has been resolved: nfsd: fix use-after-free due to delegation race A delegation break could arrive as soon as we've called vfs_setlease. A delegation break runs a callback which immediately (in nfsd4_cb_recall_prepare) adds the delegation to del_recall_lru. If we then exit nfs4_set_delegation without hashing the delegation, it will be freed as soon as the callback is done with it, without ever being removed from del_recall_lru. Symptoms show up later as use-after-free or list corruption warnings, usually in the laundromat thread. I suspect aba2072f4523 "nfsd: grant read delegations to clients holding writes" made this bug easier to hit, but I looked as far back as v3.0 and it looks to me it already had the same problem. So I'm not sure where the bug was introduced; it may have been there from the beginning.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/04a8d07f3d58308b92630045560799a3faa3ebcePatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/148c816f10fd11df27ca6a9b3238cdd42fa72cd3Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/2becaa990b93cbd2928292c0b669d3abb6cf06d4Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/33645d3e22720cac1e4548f8fef57bf0649536eePatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/348714018139c39533c55661a0c7c990671396b4Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/548ec0805c399c65ed66c6641be467f717833ab5Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e0759696de6851d7536efddfdd2dfed4c4df1f09Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/eeb0711801f5e19ef654371b627682aed3b11373Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/04a8d07f3d58308b92630045560799a3faa3ebcePatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/148c816f10fd11df27ca6a9b3238cdd42fa72cd3Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/2becaa990b93cbd2928292c0b669d3abb6cf06d4Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/33645d3e22720cac1e4548f8fef57bf0649536eePatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/348714018139c39533c55661a0c7c990671396b4Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/548ec0805c399c65ed66c6641be467f717833ab5Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/e0759696de6851d7536efddfdd2dfed4c4df1f09Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/eeb0711801f5e19ef654371b627682aed3b11373Patch



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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfsd: fix use-after-free due to delegation race\n\nA delegation break could arrive as soon as we\u0027ve called vfs_setlease.  A\ndelegation break runs a callback which immediately (in\nnfsd4_cb_recall_prepare) adds the delegation to del_recall_lru.  If we\nthen exit nfs4_set_delegation without hashing the delegation, it will be\nfreed as soon as the callback is done with it, without ever being\nremoved from del_recall_lru.\n\nSymptoms show up later as use-after-free or list corruption warnings,\nusually in the laundromat thread.\n\nI suspect aba2072f4523 \"nfsd: grant read delegations to clients holding\nwrites\" made this bug easier to hit, but I looked as far back as v3.0\nand it looks to me it already had the same problem.  So I\u0027m not sure\nwhere the bug was introduced; it may have been there from the beginning."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: nfsd: corrige el use-after-free debido a la ejecuci\u00f3n de delegaci\u00f3n. Una interrupci\u00f3n de la delegaci\u00f3n podr\u00eda llegar tan pronto como hayamos llamado a vfs_setlease. Una interrupci\u00f3n de la delegaci\u00f3n ejecuta una devoluci\u00f3n de llamada que inmediatamente (en nfsd4_cb_recall_prepare) agrega la delegaci\u00f3n a del_recall_lru. Si luego salimos de nfs4_set_delegation sin aplicar hash a la delegaci\u00f3n, se liberar\u00e1 tan pronto como finalice la devoluci\u00f3n de llamada, sin eliminarse nunca de del_recall_lru. Los s\u00edntomas aparecen m\u00e1s tarde como advertencias de use-after-free o de corrupci\u00f3n en la lista, generalmente en el hilo de la lavander\u00eda. Sospecho que aba2072f4523 \"nfsd: otorgar delegaciones de lectura a clientes que tienen escrituras\" hizo que este error fuera m\u00e1s f\u00e1cil de corregir, pero mir\u00e9 hasta la versi\u00f3n 3.0 y me parece que ya ten\u00eda el mismo problema. Entonces no estoy seguro de d\u00f3nde se introdujo el error; puede que haya estado ah\u00ed desde el principio."
    }
  ],
  "id": "CVE-2021-47506",
  "lastModified": "2025-01-06T20:44:45.983",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
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  "published": "2024-05-24T15:15:11.197",
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  "vulnStatus": "Analyzed",
  "weaknesses": [
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          "lang": "en",
          "value": "CWE-416"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
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  ]
}


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