CVE-2026-99228 (GCVE-0-2026-99228)

Vulnerability from cvelistv5 – Published: 2026-11-02 16:06 – Updated: 2026-11-03 19:12
VLAI
Title
io_uring/io-wq: don't lose the signal that ends work
Summary
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 bounded work that is started with IO_WQ_BIT_EXIT set. The bit is set before the workers are signalled, and it is tested after the flag has been cleared, with clear_notify_signal() providing the barrier. So either the flag stays, or the bit is seen. Work that is started while the io-wq exits is treated like work that is being run at that time: it isn't interrupted unless it waits interruptibly.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6637 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: afcc4015d1bf5659b8c722aff679e9b8c41ee156 , < ddccc60f036b309430cf130d48aafed94ef7355a (git)
Affected: afcc4015d1bf5659b8c722aff679e9b8c41ee156 , < 08c42055b8f9a5d29236d34ad4bce08828239fe1 (git)
Affected: afcc4015d1bf5659b8c722aff679e9b8c41ee156 , < 62996803c1b5f18176de255db4c843021f2d19c8 (git)
Affected: afcc4015d1bf5659b8c722aff679e9b8c41ee156 , < 7309fea05a3d66af9746843c43fef14c10b8141e (git)
Affected: afcc4015d1bf5659b8c722aff679e9b8c41ee156 , < fdb771015c1e13677b57a4015f0c938748f13781 (git)
Affected: afcc4015d1bf5659b8c722aff679e9b8c41ee156 , < 63c103279a95e82280092f2f4232e91e8117a252 (git)
guessed Create a notification for this product.
Linux Linux Affected: 5.12
Unaffected: 0 , < 5.12 (semver)
Unaffected: 6.1.191 , ≤ 6.1.* (semver)
Unaffected: 6.6.161 , ≤ 6.6.* (semver)
Unaffected: 6.12.115 , ≤ 6.12.* (semver)
Unaffected: 6.18.60 , ≤ 6.18.* (semver)
Unaffected: 7.2.14 , ≤ 7.2.* (semver)
Unaffected: 7.4-rc1 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/io-wq: don\u0027t lose the signal that ends work\n\nWhen a thread exits, only its tracked requests are cancelled. Then its\nio-wq is torn down. io_wq_exit_workers() signals every worker, to get it\nout of an interruptible sleep, and waits for all of them to exit. Before\nthey do, they go through the work that is left. Unbounded work is\ncancelled. Bounded work is run, as it is expected to end by itself.\n\nNot all of it does. An open has no file yet, so it counts as bounded, and\nthe open of a FIFO waits for the other end. That is what the signal is for.\nBut the workers are signalled once, and a worker that hasn\u0027t started the\nwork by then loses the signal:\n\n  io_wq_exit_workers()               io_worker_handle_work()\n    io_wq_worker_wake()\n      set TIF_NOTIFY_SIGNAL\n                                       io_assign_current_work()\n                                         io_run_task_work()\n                                           clear TIF_NOTIFY_SIGNAL\n                                       io_wq_submit_work()\n                                         fifo_open()\n                                           wait_for_partner()\n    wait_for_completion_timeout()\n\nThe thread never gets out of do_exit():\n\n  IORING_OP_OPENAT of a FIFO without a writer, IOSQE_ASYNC\n  exit of the thread that has submitted it\n\nhangs in more than 9 of 10 attempts (4 CPUs, KVM), until the process is\nkilled.\n\nSet TIF_NOTIFY_SIGNAL for bounded work that is started with IO_WQ_BIT_EXIT\nset. The bit is set before the workers are signalled, and it is tested\nafter the flag has been cleared, with clear_notify_signal() providing the\nbarrier. So either the flag stays, or the bit is seen.\n\nWork that is started while the io-wq exits is treated like work that is\nbeing run at that time: it isn\u0027t interrupted unless it waits\ninterruptibly."
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      "cve": "CVE-2026-99228",
      "id": "CVE-2026-99228",
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      "product_status:known_affected": "189",
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      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: kernel: Denial of Service via io_uring worker hang during thread exit",
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      "cve": "CVE-2026-99228",
      "id": "CVE-2026-99228",
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      "product_status:known_affected": "202",
      "product_status:known_not_affected": "143",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-99228",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/2026/cve-2026-99228.json",
      "version": "2"
    }
  }
}



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