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CVE-2021-47412 (GCVE-0-2021-47412)

Vulnerability from cvelistv5 – Published: 2024-05-21 15:04 – Updated: 2026-08-05 08:47
VLAI
Title
block: don't call rq_qos_ops->done_bio if the bio isn't tracked
Summary
In the Linux kernel, the following vulnerability has been resolved: block: don't call rq_qos_ops->done_bio if the bio isn't tracked rq_qos framework is only applied on request based driver, so: 1) rq_qos_done_bio() needn't to be called for bio based driver 2) rq_qos_done_bio() needn't to be called for bio which isn't tracked, such as bios ended from error handling code. Especially in bio_endio(): 1) request queue is referred via bio->bi_bdev->bd_disk->queue, which may be gone since request queue refcount may not be held in above two cases 2) q->rq_qos may be freed in blk_cleanup_queue() when calling into __rq_qos_done_bio() Fix the potential kernel panic by not calling rq_qos_ops->done_bio if the bio isn't tracked. This way is safe because both ioc_rqos_done_bio() and blkcg_iolatency_done_bio() are nop if the bio isn't tracked.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2024-06-11 17:28 UTC
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 67b42d0bf7a8fd1ec0cf1acdc9550e688d7c8578 , < db60edbfff332a6a5477c367af8125f034570989 (git)
Affected: 67b42d0bf7a8fd1ec0cf1acdc9550e688d7c8578 , < 004b8f8a691205a93d9e80d98b786b2b97424d6e (git)
Affected: 67b42d0bf7a8fd1ec0cf1acdc9550e688d7c8578 , < a647a524a46736786c95cdb553a070322ca096e3 (git)
guessed Create a notification for this product.
Linux Linux Affected: 4.19
Unaffected: 0 , < 4.19 (semver)
Unaffected: 5.10.241 , ≤ 5.10.* (semver)
Unaffected: 5.14.11 , ≤ 5.14.* (semver)
Unaffected: 5.15 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
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            "title": "CVE Program Container"
          },
          {
            "metrics": [
              {
                "other": {
                  "content": {
                    "id": "CVE-2021-47412",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2024-06-11T17:28:47.066559Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2024-06-11T17:28:53.752Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "defaultStatus": "unaffected",
              "product": "Linux",
              "programFiles": [
                "block/bio.c"
              ],
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "vendor": "Linux",
              "versions": [
                {
                  "lessThan": "db60edbfff332a6a5477c367af8125f034570989",
                  "status": "affected",
                  "version": "67b42d0bf7a8fd1ec0cf1acdc9550e688d7c8578",
                  "versionType": "git"
                },
                {
                  "lessThan": "004b8f8a691205a93d9e80d98b786b2b97424d6e",
                  "status": "affected",
                  "version": "67b42d0bf7a8fd1ec0cf1acdc9550e688d7c8578",
                  "versionType": "git"
                },
                {
                  "lessThan": "a647a524a46736786c95cdb553a070322ca096e3",
                  "status": "affected",
                  "version": "67b42d0bf7a8fd1ec0cf1acdc9550e688d7c8578",
                  "versionType": "git"
                }
              ]
            },
            {
              "defaultStatus": "affected",
              "product": "Linux",
              "programFiles": [
                "block/bio.c"
              ],
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "vendor": "Linux",
              "versions": [
                {
                  "status": "affected",
                  "version": "4.19"
                },
                {
                  "lessThan": "4.19",
                  "status": "unaffected",
                  "version": "0",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "5.10.*",
                  "status": "unaffected",
                  "version": "5.10.241",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "5.14.*",
                  "status": "unaffected",
                  "version": "5.14.11",
                  "versionType": "semver"
                },
                {
                  "lessThanOrEqual": "*",
                  "status": "unaffected",
                  "version": "5.15",
                  "versionType": "original_commit_for_fix"
                }
              ]
            }
          ],
          "cpeApplicability": [
            {
              "nodes": [
                {
                  "cpeMatch": [
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.10.241",
                      "versionStartIncluding": "4.19",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.14.11",
                      "versionStartIncluding": "4.19",
                      "vulnerable": true
                    },
                    {
                      "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                      "versionEndExcluding": "5.15",
                      "versionStartIncluding": "4.19",
                      "vulnerable": true
                    }
                  ],
                  "negate": false,
                  "operator": "OR"
                }
              ]
            }
          ],
          "descriptions": [
            {
              "lang": "en",
              "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nblock: don\u0027t call rq_qos_ops-\u003edone_bio if the bio isn\u0027t tracked\n\nrq_qos framework is only applied on request based driver, so:\n\n1) rq_qos_done_bio() needn\u0027t to be called for bio based driver\n\n2) rq_qos_done_bio() needn\u0027t to be called for bio which isn\u0027t tracked,\nsuch as bios ended from error handling code.\n\nEspecially in bio_endio():\n\n1) request queue is referred via bio-\u003ebi_bdev-\u003ebd_disk-\u003equeue, which\nmay be gone since request queue refcount may not be held in above two\ncases\n\n2) q-\u003erq_qos may be freed in blk_cleanup_queue() when calling into\n__rq_qos_done_bio()\n\nFix the potential kernel panic by not calling rq_qos_ops-\u003edone_bio if\nthe bio isn\u0027t tracked. This way is safe because both ioc_rqos_done_bio()\nand blkcg_iolatency_done_bio() are nop if the bio isn\u0027t tracked."
            }
          ],
          "metrics": [
            {
              "cvssV3_1": {
                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "scenarios": [
                {
                  "lang": "en",
                  "value": "AV:L - The bug is in block-layer bio_endio()/rq_qos_done_bio(), reached by local I/O submission (syscalls to a block device or filesystem on it) racing device/queue teardown, not by parsing remote protocol packets.\nAC:L - An attacker who can issue concurrent I/O and induce queue teardown (e.g. write to removable/loop/NBD media then eject/disconnect) controls both sides of the race; rq_qos_done_bio() has no lock versus rq_qos_exit(), so the UAF is reliably triggerable.\nPR:L - Unprivileged local users can write to user-accessible block devices (removable media, permitted loop/NBD nodes) and trigger teardown via eject/unmount paths available to the mounting user; root in the init namespace is not required.\nUI:N - The attacker performs the I/O and device teardown/eject themselves; no separate victim action is required.\nS:U - Impact is confined to the host kernel (UAF/panic or local privilege escalation) and does not cross a VM, IOMMU, or other security authority boundary.\nC:H - rq_qos_exit() frees rq_qos objects while bio_endio() may still load q-\u003erq_qos and walk rqos-\u003eops/next on reallocated slab memory, giving an attacker-controlled UAF read primitive.\nI:H - __rq_qos_done_bio() invokes rqos-\u003eops-\u003edone_bio on the freed object, so heap reuse can hijack the function pointer for arbitrary write / control-flow hijacking, not merely a crash.\nA:H - The same UAF produces kernel oops/panic when done_bio runs against freed rq_qos or a freed request_queue, fully impacting availability."
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-08-05T08:47:43.235Z",
            "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "shortName": "Linux"
          },
          "references": [
            {
              "url": "https://git.kernel.org/stable/c/db60edbfff332a6a5477c367af8125f034570989"
            },
            {
              "url": "https://git.kernel.org/stable/c/004b8f8a691205a93d9e80d98b786b2b97424d6e"
            },
            {
              "url": "https://git.kernel.org/stable/c/a647a524a46736786c95cdb553a070322ca096e3"
            }
          ],
          "title": "block: don\u0027t call rq_qos_ops-\u003edone_bio if the bio isn\u0027t tracked",
          "x_generator": {
            "engine": "bippy-1.2.0"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "assignerShortName": "Linux",
        "cveId": "CVE-2021-47412",
        "datePublished": "2024-05-21T15:04:03.309Z",
        "dateReserved": "2024-05-21T14:58:30.817Z",
        "dateUpdated": "2026-08-05T08:47:43.235Z",
        "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.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.


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.