ceph: fix hanging __ceph_get_caps() with stale mds_wanted

{
  "id": "7f6fc5d7d779bba5290df8b8ba1a9a914555449e908391b2318498ea9e31f2fa",
  "url": "https://osv.dev/vulnerability/CVE-2026-80527",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ceph: fix hanging __ceph_get_caps() with stale mds_wanted",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: ceph: fix hanging __ceph_get_caps() with stale mds_wanted A reader can hang forever in __ceph_get_caps() when the client no longer holds `FILE_RD`, but local cap state still says that the capability is already wanted (via `mds_wanted`). One way to trigger this is through MDS cap revocation. If another client performs a conflicting operation, the MDS can revoke `FILE_RD` from the reader; the next read then has to reacquire `FILE_RD`. If the cap update that should request `FILE_RD` never reaches the MDS after `cap->mds_wanted` was raised, the reader is left holding only non-file caps while local `mds_wanted` still includes the file read caps. In that state, try_get_cap_refs() sees `need <= mds_wanted` and returns 0, so __ceph_get_caps() just waits on `i_cap_wq`. If the cap update that was supposed to request `FILE_RD never reaches the MDS after `cap->mds_wanted was` raised, no further request is sent and the waiter can sleep indefinitely until unrelated cap traffic happens to wake it up. The ordering issue is that `cap->mds_wanted` is updated in __prep_cap() before the `CEPH_MSG_CLIENT_CAPS message` is actually queued for send. That makes one field serve two different meanings at once: what this client wants, and what the client believes the MDS already knows it wants. A proper fix would be to split those states and track whether a cap update is actually in flight or has been observed by the MDS. However, simpl",
    "evidence": "osv:CVE-2026-80527",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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            "value": "5.10.266",
            "evidence": "/affected/1/ranges"
          },
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            "evidence": "/affected/1/ranges"
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            "value": "6.1.184",
            "evidence": "/affected/1/ranges"
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            "value": "6.6.153",
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          {
            "value": "6.12.105",
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          {
            "value": "6.18.46",
            "evidence": "/affected/1/ranges"
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          {
            "value": "7.1.10",
            "evidence": "/affected/1/ranges"
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        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-80527",
      "aliases": [
        "CVE-2026-80527"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
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                  "fixed": "5e84bc6f67e19fdd192d8b215de728acbfc12572"
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                {
                  "fixed": "5fedf279a1ea369d39c8b06dd4547cdc576065d0"
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        {
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              "type": "ECOSYSTEM",
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            "ecosystem": "Linux"
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          "database_specific": {
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      "modified": "2026-10-28T02:30:43.700464473Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/50958bb928bad3bdba9e5d1b7ff4bbadcf6951e6",
        "https://git.kernel.org/stable/c/5e84bc6f67e19fdd192d8b215de728acbfc12572",
        "https://git.kernel.org/stable/c/5fedf279a1ea369d39c8b06dd4547cdc576065d0",
        "https://git.kernel.org/stable/c/9e55fe24c548ad3163903eb58bb002d28d32a630",
        "https://git.kernel.org/stable/c/a3bc6b3e9ef3f5f5cb85a902a30a090c7931127c",
        "https://git.kernel.org/stable/c/b5661524c5a45085a866864ca9b8ae2513dfd67a",
        "https://git.kernel.org/stable/c/e05c315b4da0c16ea800ee4b2cb6c617f586d1b5",
        "https://git.kernel.org/stable/c/fcce1b3be6d286aa80831e730289f4c062053ae6",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80527.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-80527",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/80xxx/CVE-2026-80527.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-80527",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 511586,
  "published_at": "2026-08-26T14:37:06.178+00:00"
}