CVE-2021-47214 (GCVE-0-2021-47214)

Vulnerability from cvelistv5 – Published: 2024-04-10 19:01 – Updated: 2026-05-23 15:19
VLAI
Title
hugetlb, userfaultfd: fix reservation restore on userfaultfd error
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.
Severity
No CVSS data available.
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2024-04-12 16:35 UTC
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: c7b1850dfb41d0b4154aca8dbc04777fbd75616f , < b5069d44e2fbc4a9093d005b3ef0949add3dd27e (git)
Affected: c7b1850dfb41d0b4154aca8dbc04777fbd75616f , < cc30042df6fcc82ea18acf0dace831503e60a0b7 (git)
Affected: 515b6124df6a84c957c5cc6bb6e8309dae7b1e9c (git)
Affected: 5.13.13 , < 5.14 (semver)
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Linux Linux Affected: 5.14
Unaffected: 0 , < 5.14 (semver)
Unaffected: 5.15.5 , ≤ 5.15.* (semver)
Unaffected: 5.16 , ≤ * (original_commit_for_fix)
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Show details on NVD website
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              "defaultStatus": "unaffected",
              "product": "Linux",
              "programFiles": [
                "mm/hugetlb.c"
              ],
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "vendor": "Linux",
              "versions": [
                {
                  "lessThan": "b5069d44e2fbc4a9093d005b3ef0949add3dd27e",
                  "status": "affected",
                  "version": "c7b1850dfb41d0b4154aca8dbc04777fbd75616f",
                  "versionType": "git"
                },
                {
                  "lessThan": "cc30042df6fcc82ea18acf0dace831503e60a0b7",
                  "status": "affected",
                  "version": "c7b1850dfb41d0b4154aca8dbc04777fbd75616f",
                  "versionType": "git"
                },
                {
                  "status": "affected",
                  "version": "515b6124df6a84c957c5cc6bb6e8309dae7b1e9c",
                  "versionType": "git"
                },
                {
                  "lessThan": "5.14",
                  "status": "affected",
                  "version": "5.13.13",
                  "versionType": "semver"
                }
              ]
            },
            {
              "defaultStatus": "affected",
              "product": "Linux",
              "programFiles": [
                "mm/hugetlb.c"
              ],
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "vendor": "Linux",
              "versions": [
                {
                  "status": "affected",
                  "version": "5.14"
                },
                {
                  "lessThan": "5.14",
                  "status": "unaffected",
                  "version": "0",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "5.15.*",
                  "status": "unaffected",
                  "version": "5.15.5",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "*",
                  "status": "unaffected",
                  "version": "5.16",
                  "versionType": "original_commit_for_fix"
                }
              ]
            }
          ],
          "cpeApplicability": [
            {
              "nodes": [
                {
                  "cpeMatch": [
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.15.5",
                      "versionStartIncluding": "5.14",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.16",
                      "versionStartIncluding": "5.14",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionStartIncluding": "5.13.13",
                      "vulnerable": true
                    }
                  ],
                  "negate": false,
                  "operator": "OR"
                }
              ]
            }
          ],
          "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."
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-05-23T15:19:32.932Z",
            "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "shortName": "Linux"
          },
          "references": [
            {
              "url": "https://git.kernel.org/stable/c/b5069d44e2fbc4a9093d005b3ef0949add3dd27e"
            },
            {
              "url": "https://git.kernel.org/stable/c/cc30042df6fcc82ea18acf0dace831503e60a0b7"
            }
          ],
          "title": "hugetlb, userfaultfd: fix reservation restore on userfaultfd error",
          "x_generator": {
            "engine": "bippy-1.2.0"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "assignerShortName": "Linux",
        "cveId": "CVE-2021-47214",
        "datePublished": "2024-04-10T19:01:54.543Z",
        "dateReserved": "2024-04-10T18:59:19.528Z",
        "dateUpdated": "2026-05-23T15:19:32.932Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.