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GHSA-7293-Q55V-843Q

Vulnerability from github – Published: 2026-05-27 15:33 – Updated: 2026-06-05 09:33

Details

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

md/md-llbitmap: fix percpu_ref not resurrected on suspend timeout

When llbitmap_suspend_timeout() times out waiting for percpu_ref to become zero, it returns -ETIMEDOUT without resurrecting the percpu_ref. The caller (md_llbitmap_daemon_fn) then continues to the next page without calling llbitmap_resume(), leaving the percpu_ref in a killed state permanently.

Fix this by resurrecting the percpu_ref before returning the error, ensuring the page control structure remains usable for subsequent operations.

Severity

7.1 (High)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-45955"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-27T14:17:12Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmd/md-llbitmap: fix percpu_ref not resurrected on suspend timeout\n\nWhen llbitmap_suspend_timeout() times out waiting for percpu_ref to\nbecome zero, it returns -ETIMEDOUT without resurrecting the percpu_ref.\nThe caller (md_llbitmap_daemon_fn) then continues to the next page\nwithout calling llbitmap_resume(), leaving the percpu_ref in a killed\nstate permanently.\n\nFix this by resurrecting the percpu_ref before returning the error,\nensuring the page control structure remains usable for subsequent\noperations.",
  "id": "GHSA-7293-q55v-843q",
  "modified": "2026-06-05T09:33:45Z",
  "published": "2026-05-27T15:33:18Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-45955"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/095417d6b669c2dec39a5842ccb94df915f97f54"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2446d099350185caeed19ab2c0270451a97296fb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d119bd2e1643cc023210ff3c6f0657e4f914e71d"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-45955 (GCVE-0-2026-45955)

Vulnerability from cvelistv5 – Published: 2026-05-27 12:18 – Updated: 2026-08-05 12:28

Title

md/md-llbitmap: fix percpu_ref not resurrected on suspend timeout

Summary

In the Linux kernel, the following vulnerability has been resolved: md/md-llbitmap: fix percpu_ref not resurrected on suspend timeout When llbitmap_suspend_timeout() times out waiting for percpu_ref to become zero, it returns -ETIMEDOUT without resurrecting the percpu_ref. The caller (md_llbitmap_daemon_fn) then continues to the next page without calling llbitmap_resume(), leaving the percpu_ref in a killed state permanently. Fix this by resurrecting the percpu_ref before returning the error, ensuring the page control structure remains usable for subsequent operations.

Severity

7.1 (High)


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

Assigner

Linux mitre root Scorecard

References

3 references

URL	Tags
https://git.kernel.org/stable/c/095417d6b669c2dec…
https://git.kernel.org/stable/c/2446d099350185cae…
https://git.kernel.org/stable/c/d119bd2e1643cc023…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 5ab829f1971dc99f2aac10846c378e67fc875abc , < 095417d6b669c2dec39a5842ccb94df915f97f54 (git) Affected: 5ab829f1971dc99f2aac10846c378e67fc875abc , < 2446d099350185caeed19ab2c0270451a97296fb (git) Affected: 5ab829f1971dc99f2aac10846c378e67fc875abc , < d119bd2e1643cc023210ff3c6f0657e4f914e71d (git)
Linux	Linux	Affected: 6.18 Unaffected: 0 , < 6.18 (semver) Unaffected: 6.18.14 , ≤ 6.18.* (semver) Unaffected: 6.19.4 , ≤ 6.19.* (semver) Unaffected: 7.0 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/md/md-llbitmap.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "095417d6b669c2dec39a5842ccb94df915f97f54",
              "status": "affected",
              "version": "5ab829f1971dc99f2aac10846c378e67fc875abc",
              "versionType": "git"
            },
            {
              "lessThan": "2446d099350185caeed19ab2c0270451a97296fb",
              "status": "affected",
              "version": "5ab829f1971dc99f2aac10846c378e67fc875abc",
              "versionType": "git"
            },
            {
              "lessThan": "d119bd2e1643cc023210ff3c6f0657e4f914e71d",
              "status": "affected",
              "version": "5ab829f1971dc99f2aac10846c378e67fc875abc",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/md/md-llbitmap.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.18"
            },
            {
              "lessThan": "6.18",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.14",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.14",
                  "versionStartIncluding": "6.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19.4",
                  "versionStartIncluding": "6.18",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.0",
                  "versionStartIncluding": "6.18",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmd/md-llbitmap: fix percpu_ref not resurrected on suspend timeout\n\nWhen llbitmap_suspend_timeout() times out waiting for percpu_ref to\nbecome zero, it returns -ETIMEDOUT without resurrecting the percpu_ref.\nThe caller (md_llbitmap_daemon_fn) then continues to the next page\nwithout calling llbitmap_resume(), leaving the percpu_ref in a killed\nstate permanently.\n\nFix this by resurrecting the percpu_ref before returning the error,\nensuring the page control structure remains usable for subsequent\noperations."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The flaw is in the MD lockless bitmap (`md-llbitmap`), reached only from the block/MD write path (`md_bitmap_start` \u2192 `llbitmap_start_write`), not from a network protocol handler. Any remote party must already cause writes through local VFS/block access (e.g., a file on an md-backed volume).\nAC:L - On a system with llbitmap enabled, an attacker can reliably force the timeout by racing the periodic daemon against many concurrent writes to the same bitmap page that hold `percpu_ref` until `daemon_sleep` expires; both sides of the race are attacker-driven I/O patterns.\nPR:L - Exploitation does not require real root in the init namespace: any principal that can issue writes to storage backed by an affected md array (typical unprivileged user on a multi-tenant NAS, or a member of the `disk` group with raw `/dev/md*` access) reaches the vulnerable code.\nUI:N - Triggering the race requires only sustained automated write I/O; no victim click, mount dialog, or other interactive action is needed beyond normal storage use.\nS:U - Impact stays within kernel/MD RAID scope (hang and bitmap inconsistency on the host); it does not cross a VM, container, or IOMMU security boundary.\nC:N - This is a refcount lifecycle logic bug, not memory corruption; there is no out-of-bounds access, UAF, or other primitive that discloses kernel memory.\nI:H - After the bug, `llbitmap_raise_barrier()` can block new writes before `llbitmap_state_machine()` runs, so dirty regions may not be recorded; combined with uncleared dirty bits on other paths, RAID resync decisions can be wrong after crash\u2014high integrity risk for redundant storage.\nA:H - A permanently killed `percpu_ref` leaves writers stuck in uninterruptible `wait_event` in `llbitmap_raise_barrier()`, causing indefinite write hangs (effective DoS) for affected bitmap pages on production NAS/RAID systems."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:28:54.212Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/095417d6b669c2dec39a5842ccb94df915f97f54"
        },
        {
          "url": "https://git.kernel.org/stable/c/2446d099350185caeed19ab2c0270451a97296fb"
        },
        {
          "url": "https://git.kernel.org/stable/c/d119bd2e1643cc023210ff3c6f0657e4f914e71d"
        }
      ],
      "title": "md/md-llbitmap: fix percpu_ref not resurrected on suspend timeout",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-45955",
    "datePublished": "2026-05-27T12:18:10.951Z",
    "dateReserved": "2026-05-13T15:03:33.088Z",
    "dateUpdated": "2026-08-05T12:28:54.212Z",
    "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.

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.
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GHSA-7293-Q55V-843Q

CVE-2026-45955 (GCVE-0-2026-45955)

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