CVE-2026-99228 — io_uring/io-wq: don't lose the signal that ends work

Affected: Linux

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

io_uring/io-wq: don't lose the signal that ends work

When a thread exits, only its tracked requests are cancelled. Then its io-wq is torn down. io_wq_exit_workers() signals every worker, to get it out of an interruptible sleep, and waits for all of them to exit. Before they do, they go through the work that is left. Unbounded work is cancelled. Bounded work is run, as it is expected to end by itself.

Not all of it does. An open has no file yet, so it counts as bounded, and the open of a FIFO waits for the other end. That is what the signal is for. But the workers are signalled once, and a worker that hasn't started the work by then loses the signal:

io_wq_exit_workers() io_worker_handle_work() io_wq_worker_wake() set TIF_NOTIFY_SIGNAL io_assign_current_work() io_run_task_work() clear TIF_NOTIFY_SIGNAL io_wq_submit_work() fifo_open() wait_for_partner() wait_for_completion_timeout()

The thread never gets out of do_exit():

IORING_OP_OPENAT of a FIFO without a writer, IOSQE_ASYNC exit of the thread that has submitted it

hangs in more than 9 of 10 attempts (4 CPUs, KVM), until the process is killed.

Set TIF_NOTIFY_SIGNAL for bound…

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CVE-2026-99228 — io_uring/io-wq: don't lose the signal that ends work