erofs: fix managed cache race for unaligned extents

{
  "id": "d4540b53244b658a1230e498e9573177f0efff7ce5959c8509d9bd6cf3ad3428",
  "url": "https://osv.dev/vulnerability/CVE-2026-64031",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "erofs: fix managed cache race for unaligned extents",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: erofs: fix managed cache race for unaligned extents After unaligned compressed extents were introduced, the following race could occur: [Thread 1] [Thread 2] (z_erofs_fill_bio_vec) ... filemap_add_folio (1) (z_erofs_bind_cache) .. .. folio_attach_private (2) filemap_add_folio (3) again Since (1) is executed but (2) hasn't been executed yet, it's possible that another thread finds the same managed folio in z_erofs_bind_cache() for a different pcluster and calls filemap_add_folio() again since folio->private is still Z_EROFS_PREALLOCATED_FOLIO. Fix this by explicitly clearing folio->private before making the folio visible in the managed cache so that another pcluster can simply wait on the locked managed folio as what we did for other shared cases [1]. This only impacts unaligned data compression (`-E48bit` with zstd, for example). [1] Commit 9e2f9d34dd12 (\"erofs: handle overlapped pclusters out of crafted images properly\") was originally introduced to handle crafted overlapped extents, but it addresses unaligned extents as well.",
    "evidence": "osv:CVE-2026-64031",
    "products": [
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        "prerequisites": [],
        "fixed_versions": [
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            "value": "7.0.11",
            "evidence": "/affected/1/ranges"
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    "severity": "high",
    "structured": {
      "id": "CVE-2026-64031",
      "aliases": [
        "CVE-2026-64031"
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      "metrics": [
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          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
        }
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      ],
      "modified": "2026-10-28T02:30:41.745646219Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/038166f873c4caf6e85cfd4ea0c5a5ba297b4e8b",
        "https://git.kernel.org/stable/c/2718cdb6db0fdbe375e61f2980aada27bafb323e",
        "https://git.kernel.org/stable/c/425d32d6288d7d845e486af9419bbedccd8c9103",
        "https://git.kernel.org/stable/c/649932fc3815eda2f24eb4de4b3a5e94886ee0b9",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64031.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-64031",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
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        "cna_assigner": "Linux",
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        "value": "CVE-2026-64031",
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
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  "source_id": "core-osv",
  "document_id": 509323,
  "published_at": "2026-07-19T15:39:21.609+00:00"
}