Vulnerability-Lookup

GHSA-4G8J-HWJQ-H8FR

Vulnerability from github – Published: 2025-12-04 18:30 – Updated: 2026-07-30 06:32

Details

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

gfs2: Fix unlikely race in gdlm_put_lock

In gdlm_put_lock(), there is a small window of time in which the DFL_UNMOUNT flag has been set but the lockspace hasn't been released, yet. In that window, dlm may still call gdlm_ast() and gdlm_bast(). To prevent it from dereferencing freed glock objects, only free the glock if the lockspace has actually been released.

Severity

7.0 (High)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2025-40242"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-12-04T16:16:17Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ngfs2: Fix unlikely race in gdlm_put_lock\n\nIn gdlm_put_lock(), there is a small window of time in which the\nDFL_UNMOUNT flag has been set but the lockspace hasn\u0027t been released,\nyet.  In that window, dlm may still call gdlm_ast() and gdlm_bast().\nTo prevent it from dereferencing freed glock objects, only free the\nglock if the lockspace has actually been released.",
  "id": "GHSA-4g8j-hwjq-h8fr",
  "modified": "2026-07-30T06:32:17Z",
  "published": "2025-12-04T18:30:52Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-40242"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/279bde3bbb0ac0bad5c729dfa85983d75a5d7641"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/28c4d9bc0708956c1a736a9e49fee71b65deee81"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4913592a3358f6ec366b8346b733d5e2360b08e1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5fdc1474e678eea1700aa266c0b7c2c96f81dd0d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/64c61b4ac645222fa7b724cef616c1f862a72a40"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2025-40242 (GCVE-0-2025-40242)

Vulnerability from cvelistv5 – Published: 2025-12-04 15:31 – Updated: 2026-08-05 12:08

Title

gfs2: Fix unlikely race in gdlm_put_lock

Summary

In the Linux kernel, the following vulnerability has been resolved: gfs2: Fix unlikely race in gdlm_put_lock In gdlm_put_lock(), there is a small window of time in which the DFL_UNMOUNT flag has been set but the lockspace hasn't been released, yet. In that window, dlm may still call gdlm_ast() and gdlm_bast(). To prevent it from dereferencing freed glock objects, only free the glock if the lockspace has actually been released.

Severity

7 (High)


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

Assigner

Linux

References

5 references

URL	Tags
https://git.kernel.org/stable/c/5fdc1474e678eea17…
https://git.kernel.org/stable/c/4913592a3358f6ec3…
https://git.kernel.org/stable/c/279bde3bbb0ac0bad…
https://git.kernel.org/stable/c/64c61b4ac645222fa…
https://git.kernel.org/stable/c/28c4d9bc0708956c1…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: d1340f80f0b8066321b499a376780da00560e857 , < 5fdc1474e678eea1700aa266c0b7c2c96f81dd0d (git) Affected: d1340f80f0b8066321b499a376780da00560e857 , < 4913592a3358f6ec366b8346b733d5e2360b08e1 (git) Affected: d1340f80f0b8066321b499a376780da00560e857 , < 279bde3bbb0ac0bad5c729dfa85983d75a5d7641 (git) Affected: d1340f80f0b8066321b499a376780da00560e857 , < 64c61b4ac645222fa7b724cef616c1f862a72a40 (git) Affected: d1340f80f0b8066321b499a376780da00560e857 , < 28c4d9bc0708956c1a736a9e49fee71b65deee81 (git) Affected: 6aa628c45875e7b8cca81ed9447a12a0e8f3504a (git) Affected: a97e75203733be0a4263a78fb7b29352be150c1c (git) Affected: 3554b46204e67333e1fb8be0e93936fb08267c80 (git) Affected: 5cff77b9827a956d076168b56775aad23bce87e4 (git) Affected: 8deedce385d220f90e435f534d71d27526273515 (git) Affected: 2225a5cd2fbc2ef0e0f78e585db3844f60416a39 (git) Affected: 02e838963fdaa6ce8570b5389aecdc6cf1fb40b0 (git) Affected: 01eb3106f43335fdc02111358dae80a5c3fd324d (git) Affected: 4.4.284 , < 4.5 (semver) Affected: 4.9.283 , < 4.10 (semver) Affected: 4.14.247 , < 4.15 (semver) Affected: 4.19.207 , < 4.20 (semver) Affected: 5.4.148 , < 5.5 (semver) Affected: 5.10.67 , < 5.11 (semver) Affected: 5.13.19 , < 5.14 (semver) Affected: 5.14.6 , < 5.15 (semver)
Linux	Linux	Affected: 5.15 Unaffected: 0 , < 5.15 (semver) Unaffected: 6.1.168 , ≤ 6.1.* (semver) Unaffected: 6.6.131 , ≤ 6.6.* (semver) Unaffected: 6.12.56 , ≤ 6.12.* (semver) Unaffected: 6.17.6 , ≤ 6.17.* (semver) Unaffected: 6.18 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/gfs2/lock_dlm.c"
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          "vendor": "Linux",
          "versions": [
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              "status": "affected",
              "version": "d1340f80f0b8066321b499a376780da00560e857",
              "versionType": "git"
            },
            {
              "lessThan": "4913592a3358f6ec366b8346b733d5e2360b08e1",
              "status": "affected",
              "version": "d1340f80f0b8066321b499a376780da00560e857",
              "versionType": "git"
            },
            {
              "lessThan": "279bde3bbb0ac0bad5c729dfa85983d75a5d7641",
              "status": "affected",
              "version": "d1340f80f0b8066321b499a376780da00560e857",
              "versionType": "git"
            },
            {
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              "versionType": "git"
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            {
              "lessThan": "28c4d9bc0708956c1a736a9e49fee71b65deee81",
              "status": "affected",
              "version": "d1340f80f0b8066321b499a376780da00560e857",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "6aa628c45875e7b8cca81ed9447a12a0e8f3504a",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "a97e75203733be0a4263a78fb7b29352be150c1c",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "3554b46204e67333e1fb8be0e93936fb08267c80",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "5cff77b9827a956d076168b56775aad23bce87e4",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "8deedce385d220f90e435f534d71d27526273515",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "2225a5cd2fbc2ef0e0f78e585db3844f60416a39",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "02e838963fdaa6ce8570b5389aecdc6cf1fb40b0",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "01eb3106f43335fdc02111358dae80a5c3fd324d",
              "versionType": "git"
            },
            {
              "lessThan": "4.5",
              "status": "affected",
              "version": "4.4.284",
              "versionType": "semver"
            },
            {
              "lessThan": "4.10",
              "status": "affected",
              "version": "4.9.283",
              "versionType": "semver"
            },
            {
              "lessThan": "4.15",
              "status": "affected",
              "version": "4.14.247",
              "versionType": "semver"
            },
            {
              "lessThan": "4.20",
              "status": "affected",
              "version": "4.19.207",
              "versionType": "semver"
            },
            {
              "lessThan": "5.5",
              "status": "affected",
              "version": "5.4.148",
              "versionType": "semver"
            },
            {
              "lessThan": "5.11",
              "status": "affected",
              "version": "5.10.67",
              "versionType": "semver"
            },
            {
              "lessThan": "5.14",
              "status": "affected",
              "version": "5.13.19",
              "versionType": "semver"
            },
            {
              "lessThan": "5.15",
              "status": "affected",
              "version": "5.14.6",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/gfs2/lock_dlm.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": "6.1.*",
              "status": "unaffected",
              "version": "6.1.168",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.131",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.56",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.17.*",
              "status": "unaffected",
              "version": "6.17.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.18",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.168",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.131",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.56",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.17.6",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18",
                  "versionStartIncluding": "5.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "4.4.284",
                  "vulnerable": true
                },
                {
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                  "versionStartIncluding": "4.9.283",
                  "vulnerable": true
                },
                {
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                  "versionStartIncluding": "4.14.247",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionStartIncluding": "4.19.207",
                  "vulnerable": true
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                  "versionStartIncluding": "5.4.148",
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                  "versionStartIncluding": "5.10.67",
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                  "versionStartIncluding": "5.14.6",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ngfs2: Fix unlikely race in gdlm_put_lock\n\nIn gdlm_put_lock(), there is a small window of time in which the\nDFL_UNMOUNT flag has been set but the lockspace hasn\u0027t been released,\nyet.  In that window, dlm may still call gdlm_ast() and gdlm_bast().\nTo prevent it from dereferencing freed glock objects, only free the\nglock if the lockspace has actually been released."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The window is opened by a local umount or a local filesystem withdraw, and the glock free is performed by local filesystem activity (inode eviction, glock shrinker, `glock_work_func`); the DLM bast that dereferences the freed object comes from an authenticated cluster peer on a private interconnect and cannot by itself create the dangling pointer. There is no network-facing service path into `gdlm_put_lock()`.\nAC:H - Exploitation requires winning a race whose opening the attacker does not control \u2014 `DFL_UNMOUNT` is set only by a root-driven umount or an error-driven withdraw \u2014 and additionally requires a DLM ast/bast for that exact resource to arrive after the free but before `dlm_release_lockspace()` completes, plus slab reuse after the RCU grace period. The author explicitly characterises it as an \"unlikely race\" in a \"small window of time\".\nPR:L - Once the teardown window is open (via administrator umount, cluster-manager failover, or a withdraw provoked by storage errors), an ordinary unprivileged user with access to the GFS2 mount drives the vulnerable side: normal file operations force glock disposal through `__gfs2_glock_put \u2192 lm_put_lock`, and creating inodes sprays `gfs2_glock_cachep` to groom the freed object. No capability check exists anywhere on that path.\nUI:N - The attacker only performs ordinary file operations on an already-mounted GFS2 filesystem; no victim must open a file, mount media, or take any deliberate action. The privileged unmount/withdraw is an environmental system state, accounted for in Attack Complexity rather than user interaction.\nS:U - The freed `struct gfs2_glock`, the DLM callback that writes into it, and any resulting corruption all live in the host kernel\u0027s own security authority. No hypervisor, IOMMU, or sandbox boundary is crossed.\nC:H - This is a use-after-free on a slab object whose contents the attacker can groom by reallocating glocks, and `gdlm_ast()` reads `gl-\u003egl_flags`, `gl-\u003egl_dstamp`, `gl-\u003egl_name.ln_type` and the `gl-\u003egl_name.ln_sbd` pointer out of the freed memory before the dead-lockref guard, using `ln_sbd` as a dereference target \u2014 giving an attacker-steerable kernel read primitive.\nI:H - Three distinct writes hit the freed object: DLM\u0027s `lksb-\u003esb_status`/`sb_flags` stores, `clear_bit(GLF_BLOCKING, \u0026gl-\u003egl_flags)`, and `gfs2_update_stats(\u0026gl-\u003egl_stats, ...)`; worse, `this_cpu_ptr(gl-\u003egl_name.ln_sbd-\u003esd_lkstats)` turns a groomed pointer in the freed object into the destination of a read-modify-write, and a surviving lockref check leads into `gfs2_glock_complete()` and `gl-\u003egl_ops` indirect calls \u2014 a control-flow hijack path.\nA:H - Dereferencing a freed glock from the DLM callback workqueue produces KASAN splats, oopses on garbage `ln_sbd`/`gl_ops` pointers, and `BUG()` in `gdlm_bast()` on an unrecognised mode, panicking the node. On a clustered filesystem, crashing the node also triggers fencing and cluster-wide recovery."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:08:46.271Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/5fdc1474e678eea1700aa266c0b7c2c96f81dd0d"
        },
        {
          "url": "https://git.kernel.org/stable/c/4913592a3358f6ec366b8346b733d5e2360b08e1"
        },
        {
          "url": "https://git.kernel.org/stable/c/279bde3bbb0ac0bad5c729dfa85983d75a5d7641"
        },
        {
          "url": "https://git.kernel.org/stable/c/64c61b4ac645222fa7b724cef616c1f862a72a40"
        },
        {
          "url": "https://git.kernel.org/stable/c/28c4d9bc0708956c1a736a9e49fee71b65deee81"
        }
      ],
      "title": "gfs2: Fix unlikely race in gdlm_put_lock",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-40242",
    "datePublished": "2025-12-04T15:31:31.497Z",
    "dateReserved": "2025-04-16T07:20:57.181Z",
    "dateUpdated": "2026-08-05T12:08:46.271Z",
    "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.

Action not permitted

GHSA-4G8J-HWJQ-H8FR

CVE-2025-40242 (GCVE-0-2025-40242)

Tags

Sightings

Nomenclature