CVE-2026-80920 (GCVE-0-2026-80920)
Vulnerability from cvelistv5
Published
2026-09-09 16:13
Modified
2026-10-21 12:47
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: io_uring: defer eventfd signaling when queued from a wakeup handler io_req_local_work_add() signals the CQ ring eventfd inline when it is the one to push the first entry onto ->work_list. For DEFER_TASKRUN rings that add is frequently done from a waitqueue wakeup handler, where an arbitrary waitqueue lock is held. eventfd_signal_mask() only refuses to recurse when current->in_eventfd is set, but that bit is set by eventfd_signal_mask() itself. If the wake chain starts somewhere else, signal goes out inline and can feed back into epoll. Add IOU_F_TWQ_IN_WAKE, set it on the task_work add done from the three waitqueue callbacks, and use it to force io_eventfd_signal() down the existing call_rcu_hurry() deferral instead of signaling inline.
References
Impacted products
Vendor Product Version
Linux Linux Version: 21a091b970cdbcf3e8ff829234b51be6f9192766
Version: 21a091b970cdbcf3e8ff829234b51be6f9192766
Version: 21a091b970cdbcf3e8ff829234b51be6f9192766
Version: 21a091b970cdbcf3e8ff829234b51be6f9192766
Version: 21a091b970cdbcf3e8ff829234b51be6f9192766
Version: 21a091b970cdbcf3e8ff829234b51be6f9192766
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{
  "containers": {
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          "programFiles": [
            "include/linux/io_uring_types.h",
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            "io_uring/eventfd.h",
            "io_uring/futex.c",
            "io_uring/io_uring.c",
            "io_uring/poll.c",
            "io_uring/tw.c",
            "io_uring/waitid.c"
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            "io_uring/eventfd.h",
            "io_uring/futex.c",
            "io_uring/io_uring.c",
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            "io_uring/tw.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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              "version": "7.2.1",
              "versionType": "semver"
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              "version": "7.3",
              "versionType": "original_commit_for_fix"
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      ],
      "cpeApplicability": [
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          "nodes": [
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              "cpeMatch": [
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring: defer eventfd signaling when queued from a wakeup handler\n\nio_req_local_work_add() signals the CQ ring eventfd inline when it is the\none to push the first entry onto -\u003ework_list. For DEFER_TASKRUN rings that\nadd is frequently done from a waitqueue wakeup handler, where an\narbitrary waitqueue lock is held.\n\neventfd_signal_mask() only refuses to recurse when current-\u003ein_eventfd\nis set, but that bit is set by eventfd_signal_mask() itself. If the wake\nchain starts somewhere else, signal goes out inline and can feed back\ninto epoll.\n\nAdd IOU_F_TWQ_IN_WAKE, set it on the task_work add done from the three\nwaitqueue callbacks, and use it to force io_eventfd_signal() down the\nexisting call_rcu_hurry() deferral instead of signaling inline."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:47:14.401Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/d0c240f25e654442a72af5ca021a02165ccce638"
        },
        {
          "url": "https://git.kernel.org/stable/c/9d984451baf768ecd9e1fdad4637b729fcb2c9d5"
        },
        {
          "url": "https://git.kernel.org/stable/c/e22f4494cc9487d326e5e3067f33dea7c1e442b2"
        },
        {
          "url": "https://git.kernel.org/stable/c/b6bb334b0e9348887e3e55e1f494b0c3b8fbf59f"
        },
        {
          "url": "https://git.kernel.org/stable/c/40b6ccf68731809ceb85c6e9f0f8f2ed61c7aa5a"
        },
        {
          "url": "https://git.kernel.org/stable/c/cd305ee3633a45fcf5f3a5d83f99f3cb77d87b6e"
        }
      ],
      "title": "io_uring: defer eventfd signaling when queued from a wakeup handler",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80920",
    "datePublished": "2026-09-09T16:13:17.023Z",
    "dateReserved": "2026-08-26T14:34:25.801Z",
    "dateUpdated": "2026-10-21T12:47:14.401Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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