sched/core: Call wakeup_preempt() for queued tasks during class change

{
  "id": "732174e6d84988706a4fd88c7a94a302beb2b19055dea618deabd87d6b7729a3",
  "url": "https://www.cve.org/CVERecord?id=CVE-2026-99205",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "sched/core: Call wakeup_preempt() for queued tasks during class change",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: sched/core: Call wakeup_preempt() for queued tasks during class change Paul reported recent RCU changes exposed a lost resched where CPU idles with a rcutorture thread waiting while being completely runnable. Dumping the rq state at the time of idling with runnable tasks showed the following: rq->next_class = &fair_sched_class rq->nr_running = 1 rq->cfs.h_nr_queued = 0 rq->rt.rt_nr_running = 1 Although the waiting task was an RT task, \"rq->next_class\" did not point to rt_sched_class and was stuck at the lower priority fair_sched_class. Inspecting sched_change_end() revealed the following race with __sched_setscheduler() for queued, but non-running tasks: CPU0 CPU1 ==== ==== __schedule() /* * rq->donor is a fair task that blocks. * rq->next_class = &fair_sched_class */ rq_lock(rq0) pick_next_task() /* nr_running = 0 */ pick_task_fair() sched_balance_newidle() raw_spin_rq_unlock(rq0) rq_lock(rq0) activate_task(rq0, p) /* p is a fair task */ rq0->nr_running++; rq0->cfs.h_nr_queued++; wakeup_preempt(rq, p) rq->next_class = &fair_sched_class resched_curr() rq_unlock(rq0) __sched_setscheduler(p) /* p is moved to SCHED_RR */ task_rq_lock(p) sched_change_begin() rq0->cfs.h_nr_queued--; rq0->rt.rt_nr_running++; sched_change_end() /* * p->on_rq = 1 (ctx->queued) * but p is not rq->donor * (!ctx->running) hence * resched_curr() is and * rq->next_class upgrade is * skipped. */ task_rq_unlock() raw_spin_rq_lock(rq0) /* * ",
    "evidence": "cve:CVE-2026-99205",
    "products": [
      {
        "name": {
          "value": "Linux",
          "evidence": "/containers/cna/affected/0/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      },
      {
        "name": {
          "value": "Linux",
          "evidence": "/containers/cna/affected/1/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-99205",
      "aliases": [
        "CVE-2026-99205"
      ],
      "metrics": [],
      "affected": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "704069649b5bfb7bf1fe32c0281fe9036806a59a",
              "lessThan": "ae89744c5ebf299bf55ac7581768fbd9f119a903",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "704069649b5bfb7bf1fe32c0281fe9036806a59a",
              "lessThan": "118a2cf4ced60777a2408001e2b4838fed1cea55",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "kernel/sched/core.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.0"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "7.0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "7.2.13",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "kernel/sched/core.c"
          ],
          "defaultStatus": "affected"
        }
      ],
      "modified": "2026-10-28T10:35:59.093Z",
      "provider": "cve",
      "references": [
        "https://git.kernel.org/stable/c/ae89744c5ebf299bf55ac7581768fbd9f119a903",
        "https://git.kernel.org/stable/c/118a2cf4ced60777a2408001e2b4838fed1cea55"
      ],
      "provider_metadata": {
        "cna": {
          "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
          "shortName": "Linux",
          "dateUpdated": "2026-10-28T10:35:59.093Z"
        }
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-99205",
        "evidence": "/cveMetadata/cveId"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-cve",
  "document_id": 425376,
  "published_at": "2026-10-28T10:35:59.093+00:00"
}