CVE-2026-99253

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: io_uring/cancel: rearm local work wake up before sleep io_uring_try_cancel_requests() sets ->cq_wait_nr to 1 so that the next io_req_local_work_add() wakes the cancelling task. The add that takes the count to zero is the only one that wakes, later ones see a count <= 0 and return. io_uring_cancel_generic() however only becomes TASK_INTERRUPTIBLE much later, so the one wake up can be spent on a running task. That is fine as long as the entry of that add is still queued, as the io_local_work_pending() check then skips the sleep. It is not if the add was delayed after queueing its entry: CPU0 (submitter in exec or exit) CPU1 (io_req_local_work_add) mpscq_push(req A) io_uring_try_cancel_requests() io_run_local_work() // runs req A io_uring_try_cancel_requests() atomic_set(&ctx->cq_wait_nr, 1) atomic_read(&ctx->cq_wait_nr) == 1 count taken, wake_up_state() // task is running, no-op prepare_to_wait(TASK_INTERRUPTIBLE) io_local_work_pending() == false schedule() mpscq_push(req B) cq_wait_nr <= 0, return Only the sleeping task can run req B, so it is stuck in execve() until a signal happens to wake it. An exiting task doesn't even get that. Arm the count again once the task state is set and before the work list is checked, for the rings whose local work this task is the one to run.

Severity

Not scored

CVSS score

Not available

Vulnerability status

Received

Source identifier

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Published

2026-11-03 12:17:32.013000

Last modified

2026-11-03 12:17:32.013000

View original CVE JSON

{
  "id": "CVE-2026-99253",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-11-03T12:17:32.013",
  "lastModified": "2026-11-03T12:17:32.013",
  "vulnStatus": "Received",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nio_uring/cancel: rearm local work wake up before sleep\n\nio_uring_try_cancel_requests() sets ->cq_wait_nr to 1 so that the next\nio_req_local_work_add() wakes the cancelling task. The add that takes the\ncount to zero is the only one that wakes, later ones see a count <= 0 and\nreturn. io_uring_cancel_generic() however only becomes\nTASK_INTERRUPTIBLE much later, so the one wake up can be spent on a\nrunning task. That is fine as long as the entry of that add is still\nqueued, as the io_local_work_pending() check then skips the sleep. It is\nnot if the add was delayed after queueing its entry:\n\nCPU0 (submitter in exec or exit)      CPU1 (io_req_local_work_add)\n                                      mpscq_push(req A)\nio_uring_try_cancel_requests()\n  io_run_local_work()  // runs req A\nio_uring_try_cancel_requests()\n  atomic_set(&ctx->cq_wait_nr, 1)\n                                      atomic_read(&ctx->cq_wait_nr) == 1\n                                      count taken, wake_up_state()\n                                        // task is running, no-op\nprepare_to_wait(TASK_INTERRUPTIBLE)\nio_local_work_pending() == false\nschedule()\n                                      mpscq_push(req B)\n                                      cq_wait_nr <= 0, return\n\nOnly the sleeping task can run req B, so it is stuck in execve() until a\nsignal happens to wake it. An exiting task doesn't even get that.\n\nArm the count again once the task state is set and before the work list\nis checked, for the rings whose local work this task is the one to run."
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "io_uring/cancel.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "d46ab2c98ababa19b41a5709b6921d7b1add7f74",
              "lessThan": "aaa06bb9fc03384f7cf2dbc3e43f2939cc7791b2",
              "versionType": "git",
              "status": "affected"
            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "io_uring/cancel.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "7.2",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "7.2",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.2.14",
              "lessThanOrEqual": "7.2.*",
              "versionType": "semver",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {},
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/aaa06bb9fc03384f7cf2dbc3e43f2939cc7791b2",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ]
}