GHSA-WG3Q-W98J-244C

Vulnerability from github – Published: 2026-08-10 15:33 – Updated: 2026-08-10 15:33
VLAI
Details

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

sched_ext: Don't warn on core-sched forced idle in put_prev_task_scx()

put_prev_task_scx() warns when a runnable task drops to a lower sched_class without SCX_OPS_ENQ_LAST, on the assumption that balance_one() would have kept it running. Core scheduling breaks that: a forced-idle SMT sibling reschedules through the core_pick fast path in pick_next_task(), which skips pick_task_scx() and thus balance_one(), so a runnable task can drop to idle with ENQ_LAST unset.

Gate the warning on sched_cpu_cookie_match(): a cookie mismatch means core scheduling forced the idle, while a match (or core scheduling off) still catches a genuine missing-ENQ_LAST drop.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-68421"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-10T13:20:35Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Don\u0027t warn on core-sched forced idle in put_prev_task_scx()\n\nput_prev_task_scx() warns when a runnable task drops to a lower sched_class\nwithout SCX_OPS_ENQ_LAST, on the assumption that balance_one() would have\nkept it running. Core scheduling breaks that: a forced-idle SMT sibling\nreschedules through the core_pick fast path in pick_next_task(), which skips\npick_task_scx() and thus balance_one(), so a runnable task can drop to idle\nwith ENQ_LAST unset.\n\nGate the warning on sched_cpu_cookie_match(): a cookie mismatch means core\nscheduling forced the idle, while a match (or core scheduling off) still\ncatches a genuine missing-ENQ_LAST drop.",
  "id": "GHSA-wg3q-w98j-244c",
  "modified": "2026-08-10T15:33:50Z",
  "published": "2026-08-10T15:33:50Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68421"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2907e9d0f05b506dfd58aec589a23042a56ef36b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b7d9c359e5cf867f7eb23df3bb1c6b9e58af24da"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e2f188cdbf8312289532c36eb4e9eb1c9544d43a"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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