Vulnerability-Lookup

GHSA-CW67-VP4W-W46P

Vulnerability from github – Published: 2025-06-18 12:30 – Updated: 2025-11-14 18:31

Details

In the Linux kernel, the following vulnerability has been resolved:

writeback: avoid use-after-free after removing device

When a disk is removed, bdi_unregister gets called to stop further writeback and wait for associated delayed work to complete. However, wb_inode_writeback_end() may schedule bandwidth estimation dwork after this has completed, which can result in the timer attempting to access the just freed bdi_writeback.

Fix this by checking if the bdi_writeback is alive, similar to when scheduling writeback work.

Since this requires wb->work_lock, and wb_inode_writeback_end() may get called from interrupt, switch wb->work_lock to an irqsafe lock.

Severity

7.8 (High)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2022-49995"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-06-18T11:15:27Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nwriteback: avoid use-after-free after removing device\n\nWhen a disk is removed, bdi_unregister gets called to stop further\nwriteback and wait for associated delayed work to complete.  However,\nwb_inode_writeback_end() may schedule bandwidth estimation dwork after\nthis has completed, which can result in the timer attempting to access the\njust freed bdi_writeback.\n\nFix this by checking if the bdi_writeback is alive, similar to when\nscheduling writeback work.\n\nSince this requires wb-\u003ework_lock, and wb_inode_writeback_end() may get\ncalled from interrupt, switch wb-\u003ework_lock to an irqsafe lock.",
  "id": "GHSA-cw67-vp4w-w46p",
  "modified": "2025-11-14T18:31:23Z",
  "published": "2025-06-18T12:30:40Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-49995"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9a6c710f3bc10bc9cc23e1c080b53245b7f9d5b7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f87904c075515f3e1d8f4a7115869d3b914674fd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f96b9f7c1676923bce871e728bb49c0dfa5013cc"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2022-49995 (GCVE-0-2022-49995)

Vulnerability from cvelistv5 – Published: 2025-06-18 11:00 – Updated: 2026-08-05 08:57

Title

writeback: avoid use-after-free after removing device

Summary

In the Linux kernel, the following vulnerability has been resolved: writeback: avoid use-after-free after removing device When a disk is removed, bdi_unregister gets called to stop further writeback and wait for associated delayed work to complete. However, wb_inode_writeback_end() may schedule bandwidth estimation dwork after this has completed, which can result in the timer attempting to access the just freed bdi_writeback. Fix this by checking if the bdi_writeback is alive, similar to when scheduling writeback work. Since this requires wb->work_lock, and wb_inode_writeback_end() may get called from interrupt, switch wb->work_lock to an irqsafe lock.

Severity

7.8 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Assigner

Linux mitre root

References

3 references

URL	Tags
https://git.kernel.org/stable/c/f96b9f7c1676923bc…
https://git.kernel.org/stable/c/9a6c710f3bc10bc9c…
https://git.kernel.org/stable/c/f87904c075515f3e1…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 45a2966fd64147518dc5bca25f447bd0fb5359ac , < f96b9f7c1676923bce871e728bb49c0dfa5013cc (git) Affected: 45a2966fd64147518dc5bca25f447bd0fb5359ac , < 9a6c710f3bc10bc9cc23e1c080b53245b7f9d5b7 (git) Affected: 45a2966fd64147518dc5bca25f447bd0fb5359ac , < f87904c075515f3e1d8f4a7115869d3b914674fd (git)
Linux	Linux	Affected: 5.15 Unaffected: 0 , < 5.15 (semver) Unaffected: 5.15.64 , ≤ 5.15.* (semver) Unaffected: 5.19.6 , ≤ 5.19.* (semver) Unaffected: 6.0 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/fs-writeback.c",
            "mm/backing-dev.c",
            "mm/page-writeback.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "f96b9f7c1676923bce871e728bb49c0dfa5013cc",
              "status": "affected",
              "version": "45a2966fd64147518dc5bca25f447bd0fb5359ac",
              "versionType": "git"
            },
            {
              "lessThan": "9a6c710f3bc10bc9cc23e1c080b53245b7f9d5b7",
              "status": "affected",
              "version": "45a2966fd64147518dc5bca25f447bd0fb5359ac",
              "versionType": "git"
            },
            {
              "lessThan": "f87904c075515f3e1d8f4a7115869d3b914674fd",
              "status": "affected",
              "version": "45a2966fd64147518dc5bca25f447bd0fb5359ac",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/fs-writeback.c",
            "mm/backing-dev.c",
            "mm/page-writeback.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.15"
            },
            {
              "lessThan": "5.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.64",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.19.*",
              "status": "unaffected",
              "version": "5.19.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.64",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.19.6",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.0",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nwriteback: avoid use-after-free after removing device\n\nWhen a disk is removed, bdi_unregister gets called to stop further\nwriteback and wait for associated delayed work to complete.  However,\nwb_inode_writeback_end() may schedule bandwidth estimation dwork after\nthis has completed, which can result in the timer attempting to access the\njust freed bdi_writeback.\n\nFix this by checking if the bdi_writeback is alive, similar to when\nscheduling writeback work.\n\nSince this requires wb-\u003ework_lock, and wb_inode_writeback_end() may get\ncalled from interrupt, switch wb-\u003ework_lock to an irqsafe lock."
        }
      ],
      "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 reached via local filesystem writeback and block-device teardown (USB/removable media, del_gendisk \u2192 bdi_unregister), not by processing remote network packets. An attacker needs local access to dirty pages on an affected device.\nAC:L - The attacker can drive both sides of the race by generating writeback I/O and then removing or ejecting the device (e.g. udisks power-off or surprise unplug), and the delayed bw_dwork (~200ms) widens the window; this UAF was hit in practice (KASAN).\nPR:L - An unprivileged user can write to auto-mounted removable storage and trigger or cause its removal without CAP_SYS_ADMIN in the init namespace. Root-only sysfs delete is not required for the worst reasonable removable-media scenario.\nUI:N - The attacker can complete the full sequence (dirty data then eject/remove the device they wrote to) without relying on a separate victim action.\nS:U - This is a host-kernel use-after-free leading to privilege escalation within the same OS security authority, not a VM escape or IOMMU/cross-boundary breakout.\nC:H - Use-after-free of the bdi_writeback object lets an attacker reclaim and control freed kernel memory, enabling arbitrary kernel read primitives.\nI:H - The same UAF is exploitable via heap spray for arbitrary kernel writes and control-flow hijacking through the delayed bandwidth-update work path.\nA:H - The freed bdi_writeback is accessed from delayed work (observed as a KASAN splat), which can oops/panic the kernel even when not fully exploited."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T08:57:04.391Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/f96b9f7c1676923bce871e728bb49c0dfa5013cc"
        },
        {
          "url": "https://git.kernel.org/stable/c/9a6c710f3bc10bc9cc23e1c080b53245b7f9d5b7"
        },
        {
          "url": "https://git.kernel.org/stable/c/f87904c075515f3e1d8f4a7115869d3b914674fd"
        }
      ],
      "title": "writeback: avoid use-after-free after removing device",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2022-49995",
    "datePublished": "2025-06-18T11:00:55.352Z",
    "dateReserved": "2025-06-18T10:57:27.387Z",
    "dateUpdated": "2026-08-05T08:57:04.391Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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