CVE-2026-99105 (GCVE-0-2026-99105)

Vulnerability from cvelistv5 – Published: 2026-10-28 10:34 – Updated: 2026-10-28 10:34
VLAI
Title
sched_ext: Fix stall when a task enqueued with SCX_ENQ_LAST lands back on its CPU's local DSQ
Summary
In the Linux kernel, the following vulnerability has been resolved: sched_ext: Fix stall when a task enqueued with SCX_ENQ_LAST lands back on its CPU's local DSQ With SCX_OPS_ENQ_LAST, the last runnable task on a CPU is passed to ops.enqueue() instead of being kept running. Exiting tasks without SCX_OPS_ENQ_EXITING, migration disabled tasks without SCX_OPS_ENQ_MIGRATION_DISABLED and tasks on an offline rq skip ops.enqueue() and go straight to the local DSQ. This happens in put_prev_task_scx() after the pick has settled on idle, so nothing reschedules the CPU, which idles with the task queued until an unrelated wakeup lands on it or the watchdog fires. scx_mitosis, which sets SCX_OPS_ENQ_LAST without SCX_OPS_ENQ_EXITING, hit this during mass cgroup teardown: exiting tasks stuck in exit_mmap() for over 40 seconds. A task put on the local DSQ runs, as anywhere else. If the SCX_ENQ_LAST enqueue left the task on this CPU's local DSQ, set need_resched on the task being switched in, as proxy_resched_idle() does. resched_curr() would flag the task being put instead, and __schedule() clears that right after the pick.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7033 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: f0e1a0643a59bf1f922fa209cec86a170b784f3f , < 8d891c218016b6145993e082e7f732cb69dd0e29 (git)
Affected: f0e1a0643a59bf1f922fa209cec86a170b784f3f , < 396ba6f04da3fd1fb5a3d1c9535bef3f967f4e59 (git)
Affected: f0e1a0643a59bf1f922fa209cec86a170b784f3f , < 7a9df76679633cf26e0fea882a684012c6ec245a (git)
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Linux Linux Affected: 6.12
Unaffected: 0 , < 6.12 (semver)
Unaffected: 6.18.59 , ≤ 6.18.* (semver)
Unaffected: 7.2.13 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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{
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          "programFiles": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Fix stall when a task enqueued with SCX_ENQ_LAST lands back on its CPU\u0027s local DSQ\n\nWith SCX_OPS_ENQ_LAST, the last runnable task on a CPU is passed to\nops.enqueue() instead of being kept running. Exiting tasks without\nSCX_OPS_ENQ_EXITING, migration disabled tasks without\nSCX_OPS_ENQ_MIGRATION_DISABLED and tasks on an offline rq skip ops.enqueue()\nand go straight to the local DSQ. This happens in put_prev_task_scx() after\nthe pick has settled on idle, so nothing reschedules the CPU, which idles\nwith the task queued until an unrelated wakeup lands on it or the watchdog\nfires.\n\nscx_mitosis, which sets SCX_OPS_ENQ_LAST without SCX_OPS_ENQ_EXITING, hit\nthis during mass cgroup teardown: exiting tasks stuck in exit_mmap() for\nover 40 seconds.\n\nA task put on the local DSQ runs, as anywhere else. If the SCX_ENQ_LAST\nenqueue left the task on this CPU\u0027s local DSQ, set need_resched on the task\nbeing switched in, as proxy_resched_idle() does. resched_curr() would flag\nthe task being put instead, and __schedule() clears that right after the\npick."
        }
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      "providerMetadata": {
        "dateUpdated": "2026-10-28T10:34:24.456Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
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          "url": "https://git.kernel.org/stable/c/7a9df76679633cf26e0fea882a684012c6ec245a"
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      "title": "sched_ext: Fix stall when a task enqueued with SCX_ENQ_LAST lands back on its CPU\u0027s local DSQ",
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  "cveMetadata": {
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    "cveId": "CVE-2026-99105",
    "datePublished": "2026-10-28T10:34:24.456Z",
    "dateReserved": "2026-09-25T10:25:14.391Z",
    "dateUpdated": "2026-10-28T10:34:24.456Z",
    "state": "PUBLISHED"
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      "date": "2026-10-29",
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        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsched_ext: Fix stall when a task enqueued with SCX_ENQ_LAST lands back on its CPU\u0027s local DSQ\n\nWith SCX_OPS_ENQ_LAST, the last runnable task on a CPU is passed to\nops.enqueue() instead of being kept running. Exiting tasks without\nSCX_OPS_ENQ_EXITING, migration disabled tasks without\nSCX_OPS_ENQ_MIGRATION_DISABLED and tasks on an offline rq skip ops.enqueue()\nand go straight to the local DSQ. This happens in put_prev_task_scx() after\nthe pick has settled on idle, so nothing reschedules the CPU, which idles\nwith the task queued until an unrelated wakeup lands on it or the watchdog\nfires.\n\nscx_mitosis, which sets SCX_OPS_ENQ_LAST without SCX_OPS_ENQ_EXITING, hit\nthis during mass cgroup teardown: exiting tasks stuck in exit_mmap() for\nover 40 seconds.\n\nA task put on the local DSQ runs, as anywhere else. If the SCX_ENQ_LAST\nenqueue left the task on this CPU\u0027s local DSQ, set need_resched on the task\nbeing switched in, as proxy_resched_idle() does. resched_curr() would flag\nthe task being put instead, and __schedule() clears that right after the\npick."
          }
        ],
        "id": "CVE-2026-99105",
        "lastModified": "2026-10-28T11:17:29.847",
        "metrics": {},
        "published": "2026-10-28T11:17:29.847",
        "references": [
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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      "cve": "CVE-2026-99105",
      "id": "CVE-2026-99105",
      "initial_release_date": "2026-10-28T00:00:00+00:00",
      "product_status:known_not_affected": "278",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: sched_ext: Fix stall when a task enqueued with SCX_ENQ_LAST lands back on its CPU\u0027s local DSQ",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-99105.json",
      "version": "3"
    }
  }
}



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