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GHSA-9C6F-R39G-MHG4

Vulnerability from github – Published: 2026-09-16 12:30 – Updated: 2026-09-16 15:30

Details

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

f2fs: only redirty pinned folios in redirty_blocks

redirty_blocks() pins folios with read_cache_folio() and then walks the same range again with filemap_lock_folio() to redirty them and drop the references it took.

Commit 5951fee46bef ("f2fs: Use a folio in redirty_blocks()") changed the second pass to a do/while loop. If read_cache_folio() fails before anything is pinned, page_idx does not advance but the cleanup loop still runs once.

If readahead has already populated the failed folio in page cache, that extra iteration finds it and folio_put_refs(folio, 2) drops one reference too many. Later drop_caches or reclaim can then report "BUG: Bad page state".

Only redirty the range that was pinned successfully.

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-2026-89841"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-16T11:16:50Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: only redirty pinned folios in redirty_blocks\n\nredirty_blocks() pins folios with read_cache_folio() and then walks the\nsame range again with filemap_lock_folio() to redirty them and drop the\nreferences it took.\n\nCommit 5951fee46bef (\"f2fs: Use a folio in redirty_blocks()\") changed\nthe second pass to a do/while loop. If read_cache_folio() fails before\nanything is pinned, page_idx does not advance but the cleanup loop still\nruns once.\n\nIf readahead has already populated the failed folio in page cache, that\nextra iteration finds it and folio_put_refs(folio, 2) drops one\nreference too many. Later drop_caches or reclaim can then report\n\"BUG: Bad page state\".\n\nOnly redirty the range that was pinned successfully.",
  "id": "GHSA-9c6f-r39g-mhg4",
  "modified": "2026-09-16T15:30:58Z",
  "published": "2026-09-16T12:30:38Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-89841"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/445e4a1e6025ecd5312e9a95c1b234192c976ca1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/85171332742e741ccd6f401c69b6e0d698119e72"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/89c65ec3c18903de763cf567c96ab3ef60e5f3b0"
    }
  ],
  "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-2026-89841 (GCVE-0-2026-89841)

Vulnerability from cvelistv5 – Published: 2026-09-16 10:31 – Updated: 2026-10-19 08:53

Title

f2fs: only redirty pinned folios in redirty_blocks

Summary

In the Linux kernel, the following vulnerability has been resolved: f2fs: only redirty pinned folios in redirty_blocks redirty_blocks() pins folios with read_cache_folio() and then walks the same range again with filemap_lock_folio() to redirty them and drop the references it took. Commit 5951fee46bef ("f2fs: Use a folio in redirty_blocks()") changed the second pass to a do/while loop. If read_cache_folio() fails before anything is pinned, page_idx does not advance but the cleanup loop still runs once. If readahead has already populated the failed folio in page cache, that extra iteration finds it and folio_put_refs(folio, 2) drops one reference too many. Later drop_caches or reclaim can then report "BUG: Bad page state". Only redirty the range that was pinned successfully.

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 CNA under the mitre root

CNA scorecard D 53/100 over 6639 records in the last 180 days details

References

3 references

URL	Tags
https://git.kernel.org/stable/c/445e4a1e6025ecd53…
https://git.kernel.org/stable/c/89c65ec3c18903de7…
https://git.kernel.org/stable/c/85171332742e741cc…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 5951fee46befbf6176c86482432f4f76e522f16c , < 445e4a1e6025ecd5312e9a95c1b234192c976ca1 (git) Affected: 5951fee46befbf6176c86482432f4f76e522f16c , < 89c65ec3c18903de763cf567c96ab3ef60e5f3b0 (git) Affected: 5951fee46befbf6176c86482432f4f76e522f16c , < 85171332742e741ccd6f401c69b6e0d698119e72 (git)
Linux	Linux	Affected: 6.16 Unaffected: 0 , < 6.16 (semver) Unaffected: 6.18.51 , ≤ 6.18.* (semver) Unaffected: 7.2.5 , ≤ 7.2.* (semver) Unaffected: 7.3 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/f2fs/file.c"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "lessThan": "445e4a1e6025ecd5312e9a95c1b234192c976ca1",
              "status": "affected",
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              "versionType": "git"
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            {
              "lessThan": "89c65ec3c18903de763cf567c96ab3ef60e5f3b0",
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              "versionType": "git"
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              "versionType": "git"
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          "programFiles": [
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          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.16"
            },
            {
              "lessThan": "6.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.51",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "6.16",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: only redirty pinned folios in redirty_blocks\n\nredirty_blocks() pins folios with read_cache_folio() and then walks the\nsame range again with filemap_lock_folio() to redirty them and drop the\nreferences it took.\n\nCommit 5951fee46bef (\"f2fs: Use a folio in redirty_blocks()\") changed\nthe second pass to a do/while loop. If read_cache_folio() fails before\nanything is pinned, page_idx does not advance but the cleanup loop still\nruns once.\n\nIf readahead has already populated the failed folio in page cache, that\nextra iteration finds it and folio_put_refs(folio, 2) drops one\nreference too many. Later drop_caches or reclaim can then report\n\"BUG: Bad page state\".\n\nOnly redirty the range that was pinned successfully."
        }
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            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
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          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - redirty_blocks() is reached only via local F2FS_IOC_COMPRESS_FILE/F2FS_IOC_DECOMPRESS_FILE ioctls (f2fs_ioctl \u2192 f2fs_ioc_{compress,decompress}_file) on a mounted f2fs file; these are not network, Bluetooth, or USB protocol handlers.\nAC:L - The attacker drives the ioctl and can force the first read_cache_folio() to fail (memcg/ENOMEM, or a fatal signal during the killable wait after readahead inserted the folio), so the do/while cleanup always runs once; no victim-timed race or layout outside their control is required.\nPR:L - Neither ioctl checks capable()/CAP_SYS_ADMIN; they need only a writable fd (FMODE_WRITE) of a compression-enabled file, and owners can set FS_COMPR_FL via FS_IOC_SETFLAGS/chattr +c on Android/embedded f2fs userdata with compress_mode=user.\nUI:N - On typical f2fs deployments (Android userdata already mounted with compression/compress_mode=user) the attacker creates or opens their own file and issues the ioctl with no victim mount, open, or other action.\nS:U - Page-cache refcount underflow and the resulting kernel oops stay inside the host kernel\u0027s security authority; this is not a VM guest-to-host escape, IOMMU bypass, or sandbox breakout.\nC:H - The extra folio_put_refs(folio, 2) drops the page-cache reference and can free a folio still indexed in mapping-\u003ei_pages; that use-after-free of page-cache memory is a read primitive for arbitrary kernel/user data.\nI:H - The same underflow lets the freed folio be reused while still in the mapping (the stray pass also dirties and unlocks it), yielding a write primitive usable for control-flow hijack.\nA:H - If the folio is absent, filemap_lock_folio() returns ERR_PTR(-ENOENT) and production f2fs_bug_on() WARNs then dereferences it (oops); the extra-put path reports BUG: Bad page state on reclaim/drop_caches and can panic."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T08:53:34.362Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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          "url": "https://git.kernel.org/stable/c/89c65ec3c18903de763cf567c96ab3ef60e5f3b0"
        },
        {
          "url": "https://git.kernel.org/stable/c/85171332742e741ccd6f401c69b6e0d698119e72"
        }
      ],
      "title": "f2fs: only redirty pinned folios in redirty_blocks",
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        "engine": "bippy-1.2.0"
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    "datePublished": "2026-09-16T10:31:15.578Z",
    "dateReserved": "2026-09-11T19:38:34.770Z",
    "dateUpdated": "2026-10-19T08:53:34.362Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
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}

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.

Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

Order JSON

How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

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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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