{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-99205",
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "state": "PUBLISHED",
        "assignerShortName": "Linux",
        "dateReserved": "2026-09-25T10:25:14.401Z",
        "datePublished": "2026-10-28T10:35:59.093Z",
        "dateUpdated": "2026-10-28T10:35:59.093Z"
    },
    "containers": {
        "cna": {
            "providerMetadata": {
                "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
                "shortName": "Linux",
                "dateUpdated": "2026-10-28T10:35:59.093Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched/core: Call wakeup_preempt() for queued tasks during class change\n\nPaul reported recent RCU changes exposed a lost resched where CPU idles\nwith a rcutorture thread waiting while being completely runnable.\n\nDumping the rq state at the time of idling with runnable tasks showed\nthe following:\n\n  rq->next_class = &fair_sched_class\n  rq->nr_running = 1\n  rq->cfs.h_nr_queued = 0\n  rq->rt.rt_nr_running = 1\n\nAlthough the waiting task was an RT task, \"rq->next_class\" did not point\nto rt_sched_class and was stuck at the lower priority fair_sched_class.\n\nInspecting sched_change_end() revealed the following race with\n__sched_setscheduler() for queued, but non-running tasks:\n\n    CPU0                                   CPU1\n    ====                                   ====\n\n  __schedule()\n\n    /*\n     * rq->donor is a fair task that blocks.\n     * rq->next_class = &fair_sched_class\n     */\n\n    rq_lock(rq0)\n\n    pick_next_task()\n      /* nr_running = 0 */\n      pick_task_fair()\n        sched_balance_newidle()\n          raw_spin_rq_unlock(rq0)\n                                    rq_lock(rq0)\n\n                                    activate_task(rq0, p)\n                                      /* p is a fair task */\n                                      rq0->nr_running++;\n                                      rq0->cfs.h_nr_queued++;\n                                      wakeup_preempt(rq, p)\n                                        rq->next_class = &fair_sched_class\n                                        resched_curr()\n\n                                    rq_unlock(rq0)\n\n                                    __sched_setscheduler(p)\n                                      /* p is moved to SCHED_RR */\n                                      task_rq_lock(p)\n                                      sched_change_begin()\n\n\t\t\t\t      rq0->cfs.h_nr_queued--;\n\t\t\t\t      rq0->rt.rt_nr_running++;\n\n                                      sched_change_end()\n                                        /*\n                                         * p->on_rq = 1 (ctx->queued)\n                                         * but p is not rq->donor\n                                         * (!ctx->running) hence\n                                         * resched_curr() is and\n                                         * rq->next_class upgrade is\n                                         * skipped.\n                                         */\n\n                                       task_rq_unlock()\n\n          raw_spin_rq_lock(rq0)\n\n          /*\n           * rq->nr_running = 1\n           * rq->cfs.h_nr_queued = 0\n           * rq->rt.rt_nr_running = 1\n           * rq->next_class = &fair_sched_class\n           */\n\n           if (rq->cfs.h_nr_queued && ...)\n             /* Above is false */\n\n           if (rq_modified_above(this_rq, &fair_sched_class))\n             /* Also false since rq->next_class is still fair */\n\n      /*\n       * sched_balance_newidle() is considered to\n       * have failed to pull any fair tasks and no\n       * other wakeups were detected.\n       */\n       return NULL; /* pick_task_fair() */\n\n    pick_task_idle()\n      return rq->idle;\n\n    next = rq->idle;\n\n    /* Preemption indicators are lost */\n    clear_tsk_need_resched(prev);\n    clear_preempt_need_resched();\n\n    rq->curr = rq->idle;\n\n  !!! rq->idle switches in with rq->running == 1 but !need_resched() !!!\n\nIn simple words, enqueue, followed by a class change of the newly queued\ntask goes unnoticed in rq->next_class indicator and\nsched_balance_newidle() sees no fair task, nor any higher priority task\nenqueued.\n\nThe above sequence will lead to CPU idling with a runnable task on the\nCPU.\n\nCall wakeup_preempt() for ctx->queued cases in sched_change_end() to\nre-evaluate rq->next_class after class change (ENQUEUE_CLASS) and set\nthe NEED_RESCHED indicator accordingly.\n\nNewidle balance will correctly see an enqueue of a higher priority\nt\n---truncated---"
                }
            ],
            "affected": [
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "kernel/sched/core.c"
                    ],
                    "versions": [
                        {
                            "version": "704069649b5bfb7bf1fe32c0281fe9036806a59a",
                            "lessThan": "ae89744c5ebf299bf55ac7581768fbd9f119a903",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "704069649b5bfb7bf1fe32c0281fe9036806a59a",
                            "lessThan": "118a2cf4ced60777a2408001e2b4838fed1cea55",
                            "status": "affected",
                            "versionType": "git"
                        }
                    ]
                },
                {
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "kernel/sched/core.c"
                    ],
                    "versions": [
                        {
                            "version": "7.0",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "7.0",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.2.13",
                            "lessThanOrEqual": "7.2.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.3",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }
            ],
            "cpeApplicability": [
                {
                    "nodes": [
                        {
                            "operator": "OR",
                            "negate": false,
                            "cpeMatch": [
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "7.0",
                                    "versionEndExcluding": "7.2.13"
                                },
                                {
                                    "vulnerable": true,
                                    "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                                    "versionStartIncluding": "7.0",
                                    "versionEndExcluding": "7.3"
                                }
                            ]
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://git.kernel.org/stable/c/ae89744c5ebf299bf55ac7581768fbd9f119a903"
                },
                {
                    "url": "https://git.kernel.org/stable/c/118a2cf4ced60777a2408001e2b4838fed1cea55"
                }
            ],
            "title": "sched/core: Call wakeup_preempt() for queued tasks during class change",
            "x_generator": {
                "engine": "bippy-1.2.0"
            }
        }
    }
}