CVE-2026-99243

kernel: kernel: Denial of Service via race condition in io_uring workqueue termination

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Published Nov 3, 2026 CVSS 3.1 · 4.7 Medium EPSS n/a KEV · Not listed
Description
This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.

Remediation

No solution or workaround provided in the CVE record

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Advisories

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History
Type Values Removed Values Added
Description 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(). This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.
Title io-wq: order the exit bit against worker creation task work Kernel workqueue deadlock caused by missing memory barrier during I/O worker cleanup
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Type Values Removed Values Added
Weaknesses CWE-665
Type Values Removed Values Added
First Time appeared Linux linux
Vendors & Products Linux linux
Type Values Removed Values Added
Description 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().
Title io-wq: order the exit bit against worker creation task work
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References
Earlier changes (2)
Weaknesses

Sources

Status
REJECTED
Assigner
Linux
Published
Updated
Nov 4, 2026, 6:21 PM
Reserved
Sep 25, 2026, 10:25 AM

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Status
Rejected
Published
Nov 3, 2026, 12:17 PM
Modified
Nov 9, 2026, 8:10 PM

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Severity
Moderate
Public date
Nov 3, 2026, 11:14 AM

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