io_uring/io-wq: don't hide a link from cancellations

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-99255
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-11-03 12:17:32 UTC
Updated2026-11-06 18:18:33 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: io_uring/io-wq: don't hide a link from cancellations A task that exits cancels its tracked requests and waits until they are gone. io_uring_cancel_generic() looks everywhere a request can be, and goes to sleep if it found nothing to cancel. It is woken up each time one of the requests of the task is completed by task work or freed. When io-wq is done with a request that has a link, there is a time in which the next request of the link can't be found: io_worker_handle_work() io_assign_current_work(worker, NULL) io_wq_free_work(work) io_req_find_next() // takes the link off the request io_free_req() // task work for the task io_assign_current_work(worker, linked) io_run_task_work() cond_resched() worker->cur_work = linked It is not pending, it is not the current work of a worker, and it is not yet on the list that it is about to be parked on. If the pass that the exiting task makes because of io_free_req() falls into that time, it finds nothing and the task goes to sleep. The worker then runs the link, which IO_WQ_BIT_EXIT doesn't prevent for bounded work. If that parks the request nothing is completed or freed, and nobody wakes up the task. If it is the process that exits it can't be killed any more either. NOP, IOSQE_ASYNC | IOSQE_IO_LINK FUTEX_WAIT, FUTEX2_PRIVATE exit of the thread, or of the process, up to 63us later With four of these per round 5 to 8 of 10,000 rounds hang (4 CPUs, KVM): io_uring_cancel_generic do_exit Commit f8b632e89a10 ("io_uring: tighten task exit cancellations") is about the same gap, and makes the task look again for whatever happens before io_free_req(). Free the request once the link is the current work of the worker, or pending. Whoever is woken up by that can find the link, until it is parked where cancellations look as well. To do so split io_wq_free_work() in two.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 768134d4f48109b90f4248feecbeeb7d684e410c 98470f164286f7f62aaee519d4d11b9370ce6d7b git Not specified
CNA Linux Linux affected 768134d4f48109b90f4248feecbeeb7d684e410c d39ebc7a583d650b1d6da9b45e2ce96ad4d877e4 git Not specified
CNA Linux Linux affected 768134d4f48109b90f4248feecbeeb7d684e410c ebe8e97fb99d9f374c482902a00677cfd24a6c27 git Not specified
CNA Linux Linux affected 768134d4f48109b90f4248feecbeeb7d684e410c 3e02b8df0e9fa1423ac2a4e03409a9329c30ac49 git Not specified
CNA Linux Linux affected 768134d4f48109b90f4248feecbeeb7d684e410c 92e20e9c72bdf6cfa6f84eded7b33399bc7061da git Not specified
CNA Linux Linux affected 768134d4f48109b90f4248feecbeeb7d684e410c 59e45f44c3cea9f4b2d099171c3cec1d25c5b638 git Not specified
CNA Linux Linux affected 768134d4f48109b90f4248feecbeeb7d684e410c 436d48a2ed13112d2d27085325838e5bce6b4507 git Not specified
CNA Linux Linux affected 5.5 Not specified
CNA Linux Linux unaffected 5.5 semver Not specified
CNA Linux Linux unaffected 6.1.191 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.161 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.115 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.60 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.14 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3.2 7.3.* semver Not specified
CNA Linux Linux unaffected 7.4-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/59e45f44c3cea9f4b2d099171c3cec1d25c5b638 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/436d48a2ed13112d2d27085325838e5bce6b4507 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/92e20e9c72bdf6cfa6f84eded7b33399bc7061da 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d39ebc7a583d650b1d6da9b45e2ce96ad4d877e4 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3e02b8df0e9fa1423ac2a4e03409a9329c30ac49 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/ebe8e97fb99d9f374c482902a00677cfd24a6c27 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/98470f164286f7f62aaee519d4d11b9370ce6d7b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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