io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period

{
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  "url": "https://osv.dev/vulnerability/CVE-2025-21655",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period io_eventfd_do_signal() is invoked from an RCU callback, but when dropping the reference to the io_ev_fd, it calls io_eventfd_free() directly if the refcount drops to zero. This isn't correct, as any potential freeing of the io_ev_fd should be deferred another RCU grace period. Just call io_eventfd_put() rather than open-code the dec-and-test and free, which will correctly defer it another RCU grace period.",
    "evidence": "osv:CVE-2025-21655",
    "products": [
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        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
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        "prerequisites": [],
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            "value": "6.1.125",
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          {
            "value": "6.6.72",
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          {
            "value": "6.12.10",
            "evidence": "/affected/1/ranges"
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    "severity": "high",
    "structured": {
      "id": "CVE-2025-21655",
      "aliases": [
        "CVE-2025-21655"
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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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              "type": "ECOSYSTEM",
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            "name": "Kernel",
            "ecosystem": "Linux"
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          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-21655.json"
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      ],
      "modified": "2026-10-28T02:30:31.805620921Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-019113.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-457936.html",
        "https://git.kernel.org/stable/c/6b63308c28987c6010b1180c72a6db4df6c68033",
        "https://git.kernel.org/stable/c/8efff2aa2d95dc437ab67c5b4a9f1d3f367baa10",
        "https://git.kernel.org/stable/c/a7085c3ae43b86d4b3d1b8275e6a67f14257e3b7",
        "https://git.kernel.org/stable/c/c9a40292a44e78f71258b8522655bffaf5753bdb",
        "https://lists.debian.org/debian-lts-announce/2025/03/msg00001.html",
        "https://project-zero.issues.chromium.org/issues/388499293",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/21xxx/CVE-2025-21655.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-21655",
        "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/2025/21xxx/CVE-2025-21655.json"
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    "related_cves": [
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        "value": "CVE-2025-21655",
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
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  "source_id": "core-osv",
  "document_id": 498376,
  "published_at": "2025-01-20T13:48:40.544+00:00"
}