GHSA-F2F3-P4R7-62CX

Vulnerability from github – Published: 2026-11-03 12:31 – Updated: 2026-11-03 21:32
VLAI
Details

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

io-wq: order the exit bit against worker creation task work

io_wq_exit_workers() cancels task work for queued worker creation with task_work_cancel_match(). That has a plain load of task->task_works.

io_queue_worker_create() adds the new entry and tests IO_WQ_BIT_EXIT to cancel it if the workqueue is already on its way out.

That must be ordered. task_work_add() has a full barrier via cmpxchg(). But io_wq_exit_start() sets the bit with set_bit() which doesn't have any memory ordering.

So afaict, on weakly ordered architectures the exiting task may load task_works before the store of the bit is visible. The other side tests the bit before the store is visible as well. So the entry remains queued with worker_refs and the exiting task waits on worker_done indefinitely.

If the task still has rings then io_uring_del_tctx_node() provides the barrier via test_and_set_bit() in io_wq_set_exit_on_idle(). When it has closed all rings though that barrier is gone.

Add the barrier after the set_bit().

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{
  "affected": [],
  "aliases": [
    "CVE-2026-99243"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-11-03T12:17:30Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nio-wq: order the exit bit against worker creation task work\n\nio_wq_exit_workers() cancels task work for queued worker creation with\ntask_work_cancel_match(). That has a plain load of task-\u003etask_works.\n\nio_queue_worker_create() adds the new entry and tests IO_WQ_BIT_EXIT to\ncancel it if the workqueue is already on its way out.\n\nThat must be ordered. task_work_add() has a full barrier via cmpxchg().\nBut io_wq_exit_start() sets the bit with set_bit() which doesn\u0027t have\nany memory ordering.\n\nSo afaict, on weakly ordered architectures the exiting task may load\ntask_works before the store of the bit is visible. The other side tests\nthe bit before the store is visible as well. So the entry remains queued\nwith worker_refs and the exiting task waits on worker_done indefinitely.\n\nIf the task still has rings then io_uring_del_tctx_node() provides the\nbarrier via test_and_set_bit() in io_wq_set_exit_on_idle(). When it\nhas closed all rings though that barrier is gone.\n\nAdd the barrier after the set_bit().",
  "id": "GHSA-f2f3-p4r7-62cx",
  "modified": "2026-11-03T21:32:06Z",
  "published": "2026-11-03T12:31:49Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99243"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0d81cdd433b0a96c5275c01b8172e0b1f71dd595"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0e5663856b69219ef2f02e04bac9f5c5be19718a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1432d881d99584105122760133caeff1dce7a9f7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/31fc780b75b278d37700373d54a99fdb4117fdd6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/67da3eec264aeb67835886720243ae2dc1463315"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6cf012a4d5e461c788ecc9dbed67adc31a142644"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/75395db7a9b40a2e826c838e648fef8ed1a2d174"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a63c752157eacf49f628359822666b32503d194a"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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