CVE-2026-99105 (GCVE-0-2026-99105)
Vulnerability from cvelistv5
Published
2026-10-28 10:34
Modified
2026-10-28 10:34
Severity ?
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.
Impacted products
Vendor Product Version
Linux Linux Version: f0e1a0643a59bf1f922fa209cec86a170b784f3f
Version: f0e1a0643a59bf1f922fa209cec86a170b784f3f
Version: f0e1a0643a59bf1f922fa209cec86a170b784f3f
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/sched/ext/ext.c",
            "kernel/sched/ext/internal.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "8d891c218016b6145993e082e7f732cb69dd0e29",
              "status": "affected",
              "version": "f0e1a0643a59bf1f922fa209cec86a170b784f3f",
              "versionType": "git"
            },
            {
              "lessThan": "396ba6f04da3fd1fb5a3d1c9535bef3f967f4e59",
              "status": "affected",
              "version": "f0e1a0643a59bf1f922fa209cec86a170b784f3f",
              "versionType": "git"
            },
            {
              "lessThan": "7a9df76679633cf26e0fea882a684012c6ec245a",
              "status": "affected",
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              "versionType": "git"
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          ]
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        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/sched/ext/ext.c",
            "kernel/sched/ext/internal.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.12"
            },
            {
              "lessThan": "6.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.59",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.13",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
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              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.59",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
                },
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-28T10:34:24.456Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/8d891c218016b6145993e082e7f732cb69dd0e29"
        },
        {
          "url": "https://git.kernel.org/stable/c/396ba6f04da3fd1fb5a3d1c9535bef3f967f4e59"
        },
        {
          "url": "https://git.kernel.org/stable/c/7a9df76679633cf26e0fea882a684012c6ec245a"
        }
      ],
      "title": "sched_ext: Fix stall when a task enqueued with SCX_ENQ_LAST lands back on its CPU\u0027s local DSQ",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "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"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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