fkie_cve-2021-47214
Vulnerability from fkie_nvd
Published
2024-04-10 19:15
Modified
2025-03-27 21:05
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: hugetlb, userfaultfd: fix reservation restore on userfaultfd error Currently in the is_continue case in hugetlb_mcopy_atomic_pte(), if we bail out using "goto out_release_unlock;" in the cases where idx >= size, or !huge_pte_none(), the code will detect that new_pagecache_page == false, and so call restore_reserve_on_error(). In this case I see restore_reserve_on_error() delete the reservation, and the following call to remove_inode_hugepages() will increment h->resv_hugepages causing a 100% reproducible leak. We should treat the is_continue case similar to adding a page into the pagecache and set new_pagecache_page to true, to indicate that there is no reservation to restore on the error path, and we need not call restore_reserve_on_error(). Rename new_pagecache_page to page_in_pagecache to make that clear.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b5069d44e2fbc4a9093d005b3ef0949add3dd27ePatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/cc30042df6fcc82ea18acf0dace831503e60a0b7Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/b5069d44e2fbc4a9093d005b3ef0949add3dd27ePatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/cc30042df6fcc82ea18acf0dace831503e60a0b7Patch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel 5.13.13
linux linux_kernel 5.16


To clipboard 

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "53E796CA-D377-4F91-8FF4-33D9CAC9A4B8",
              "versionEndExcluding": "5.15.5",
              "versionStartIncluding": "5.14",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:5.13.13:*:*:*:*:*:*:*",
              "matchCriteriaId": "6047C65C-29BB-4EDB-B410-FA269D2877D5",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:5.16:rc1:*:*:*:*:*:*",
              "matchCriteriaId": "357AA433-37E8-4323-BFB2-3038D6E4B414",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nhugetlb, userfaultfd: fix reservation restore on userfaultfd error\n\nCurrently in the is_continue case in hugetlb_mcopy_atomic_pte(), if we\nbail out using \"goto out_release_unlock;\" in the cases where idx \u003e=\nsize, or !huge_pte_none(), the code will detect that new_pagecache_page\n== false, and so call restore_reserve_on_error().  In this case I see\nrestore_reserve_on_error() delete the reservation, and the following\ncall to remove_inode_hugepages() will increment h-\u003eresv_hugepages\ncausing a 100% reproducible leak.\n\nWe should treat the is_continue case similar to adding a page into the\npagecache and set new_pagecache_page to true, to indicate that there is\nno reservation to restore on the error path, and we need not call\nrestore_reserve_on_error().  Rename new_pagecache_page to\npage_in_pagecache to make that clear."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: hugetlb, userfaultfd: se corrige el error de restauraci\u00f3n de reserva en userfaultfd Actualmente, en el caso is_continue en hugetlb_mcopy_atomic_pte(), si salimos usando \"goto out_release_unlock;\" en los casos donde idx \u0026gt;= size, o !huge_pte_none(), el c\u00f3digo detectar\u00e1 que new_pagecache_page == false, y por lo tanto llamar\u00e1 a restore_reserve_on_error(). En este caso, veo que restore_reserve_on_error() elimina la reserva, y la siguiente llamada a remove_inode_hugepages() incrementar\u00e1 h-\u0026gt;resv_hugepages causando una fuga 100% reproducible. Deber\u00edamos tratar el caso is_continue de forma similar a agregar una p\u00e1gina al pagecache y establecer new_pagecache_page en true, para indicar que no hay ninguna reserva para restaurar en la ruta del error, y no necesitamos llamar a restore_reserve_on_error(). Cambie el nombre new_pagecache_page a page_in_pagecache para que quede claro."
    }
  ],
  "id": "CVE-2021-47214",
  "lastModified": "2025-03-27T21:05:27.253",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2024-04-10T19:15:48.680",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/b5069d44e2fbc4a9093d005b3ef0949add3dd27e"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/cc30042df6fcc82ea18acf0dace831503e60a0b7"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/b5069d44e2fbc4a9093d005b3ef0949add3dd27e"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/cc30042df6fcc82ea18acf0dace831503e60a0b7"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-401"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}


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