GHSA-55FV-CCJV-2HR3

Vulnerability from github – Published: 2026-03-25 12:30 – Updated: 2026-03-25 12:30
VLAI?
Details

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

sched/deadline: Fix missing ENQUEUE_REPLENISH during PI de-boosting

Running stress-ng --schedpolicy 0 on an RT kernel on a big machine might lead to the following WARNINGs (edited).

sched: DL de-boosted task PID 22725: REPLENISH flag missing

WARNING: CPU: 93 PID: 0 at kernel/sched/deadline.c:239 dequeue_task_dl+0x15c/0x1f8 ... (running_bw underflow) Call trace: dequeue_task_dl+0x15c/0x1f8 (P) dequeue_task+0x80/0x168 deactivate_task+0x24/0x50 push_dl_task+0x264/0x2e0 dl_task_timer+0x1b0/0x228 __hrtimer_run_queues+0x188/0x378 hrtimer_interrupt+0xfc/0x260 ...

The problem is that when a SCHED_DEADLINE task (lock holder) is changed to a lower priority class via sched_setscheduler(), it may fail to properly inherit the parameters of potential DEADLINE donors if it didn't already inherit them in the past (shorter deadline than donor's at that time). This might lead to bandwidth accounting corruption, as enqueue_task_dl() won't recognize the lock holder as boosted.

The scenario occurs when: 1. A DEADLINE task (donor) blocks on a PI mutex held by another DEADLINE task (holder), but the holder doesn't inherit parameters (e.g., it already has a shorter deadline) 2. sched_setscheduler() changes the holder from DEADLINE to a lower class while still holding the mutex 3. The holder should now inherit DEADLINE parameters from the donor and be enqueued with ENQUEUE_REPLENISH, but this doesn't happen

Fix the issue by introducing __setscheduler_dl_pi(), which detects when a DEADLINE (proper or boosted) task gets setscheduled to a lower priority class. In case, the function makes the task inherit DEADLINE parameters of the donoer (pi_se) and sets ENQUEUE_REPLENISH flag to ensure proper bandwidth accounting during the next enqueue operation.

Show details on source website

{
  "affected": [],
  "aliases": [
    "CVE-2026-23371"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-03-25T11:16:36Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched/deadline: Fix missing ENQUEUE_REPLENISH during PI de-boosting\n\nRunning stress-ng --schedpolicy 0 on an RT kernel on a big machine\nmight lead to the following WARNINGs (edited).\n\n sched: DL de-boosted task PID 22725: REPLENISH flag missing\n\n WARNING: CPU: 93 PID: 0 at kernel/sched/deadline.c:239 dequeue_task_dl+0x15c/0x1f8\n ... (running_bw underflow)\n Call trace:\n  dequeue_task_dl+0x15c/0x1f8 (P)\n  dequeue_task+0x80/0x168\n  deactivate_task+0x24/0x50\n  push_dl_task+0x264/0x2e0\n  dl_task_timer+0x1b0/0x228\n  __hrtimer_run_queues+0x188/0x378\n  hrtimer_interrupt+0xfc/0x260\n  ...\n\nThe problem is that when a SCHED_DEADLINE task (lock holder) is\nchanged to a lower priority class via sched_setscheduler(), it may\nfail to properly inherit the parameters of potential DEADLINE donors\nif it didn\u0027t already inherit them in the past (shorter deadline than\ndonor\u0027s at that time). This might lead to bandwidth accounting\ncorruption, as enqueue_task_dl() won\u0027t recognize the lock holder as\nboosted.\n\nThe scenario occurs when:\n1. A DEADLINE task (donor) blocks on a PI mutex held by another\n   DEADLINE task (holder), but the holder doesn\u0027t inherit parameters\n   (e.g., it already has a shorter deadline)\n2. sched_setscheduler() changes the holder from DEADLINE to a lower\n   class while still holding the mutex\n3. The holder should now inherit DEADLINE parameters from the donor\n   and be enqueued with ENQUEUE_REPLENISH, but this doesn\u0027t happen\n\nFix the issue by introducing __setscheduler_dl_pi(), which detects when\na DEADLINE (proper or boosted) task gets setscheduled to a lower\npriority class. In case, the function makes the task inherit DEADLINE\nparameters of the donoer (pi_se) and sets ENQUEUE_REPLENISH flag to\nensure proper bandwidth accounting during the next enqueue operation.",
  "id": "GHSA-55fv-ccjv-2hr3",
  "modified": "2026-03-25T12:30:24Z",
  "published": "2026-03-25T12:30:24Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23371"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ba1c22924ddcc280672a2a06a9ca99ee3a1b92c3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d658686a1331db3bb108ca079d76deb3208ed949"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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