CVE-2026-98286 (GCVE-0-2026-98286)
Vulnerability from cvelistv5
Published
2026-10-06 08:45
Modified
2026-10-19 09:16
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: drop_monitor: use timer_shutdown_sync() to prevent timer rearming during teardown In drop_monitor teardown paths (net_dm_trace_off_set(), net_dm_hw_monitor_stop(), and error unwind paths in net_dm_trace_on_set() and net_dm_hw_monitor_start()), per-CPU timers are stopped using timer_delete_sync() followed by cancel_work_sync(). However, there is a circular dependency between send_timer and dm_alert_work: 1) sched_send_work() (timer callback) schedules dm_alert_work. 2) send_dm_alert() / net_dm_hw_summary_work() calls reset_per_cpu_data() or net_dm_hw_reset_per_cpu_data(). 3) If memory allocation fails under memory pressure in the reset function, it re-arms the timer via mod_timer(&data->send_timer, ...). If dm_alert_work is running concurrently while timer_delete_sync() executes on another CPU, an allocation failure in the worker will re-arm the timer after timer_delete_sync() has already returned. Once cancel_work_sync() completes and module_put() is called, the timer remains active in the timer wheel. If the module is then unloaded, the timer will fire and execute sched_send_work() in freed memory, triggering a kernel panic / use-after-free. Switch from timer_delete_sync() to timer_shutdown_sync(). This guarantees that any in-flight timer handler has finished and prevents subsequent re-arming attempts from running workers from succeeding. When monitoring is restarted later, timer_setup() is invoked, which cleanly re-initializes the timer.
References
Impacted products
Vendor Product Version
Linux Linux Version: 9398e9c0b1d44eeb700e9e766c02bcc765c82570
Version: 9398e9c0b1d44eeb700e9e766c02bcc765c82570
Version: 9398e9c0b1d44eeb700e9e766c02bcc765c82570
Version: 2514c7ad115e762562c7bdd58bb1ab3425a98245
Version: 439b1164da3612ec7e186e1dc314471e7190bfc7
Version: 5.10.27   ≤
Version: 5.11.11   ≤
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{
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrop_monitor: use timer_shutdown_sync() to prevent timer rearming during teardown\n\nIn drop_monitor teardown paths (net_dm_trace_off_set(),\nnet_dm_hw_monitor_stop(), and error unwind paths in net_dm_trace_on_set()\nand net_dm_hw_monitor_start()), per-CPU timers are stopped using\ntimer_delete_sync() followed by cancel_work_sync().\n\nHowever, there is a circular dependency between send_timer and\ndm_alert_work:\n1) sched_send_work() (timer callback) schedules dm_alert_work.\n2) send_dm_alert() / net_dm_hw_summary_work() calls reset_per_cpu_data()\n   or net_dm_hw_reset_per_cpu_data().\n3) If memory allocation fails under memory pressure in the reset\n   function, it re-arms the timer via mod_timer(\u0026data-\u003esend_timer, ...).\n\nIf dm_alert_work is running concurrently while timer_delete_sync()\nexecutes on another CPU, an allocation failure in the worker will\nre-arm the timer after timer_delete_sync() has already returned.\nOnce cancel_work_sync() completes and module_put() is called, the timer\nremains active in the timer wheel. If the module is then unloaded, the\ntimer will fire and execute sched_send_work() in freed memory,\ntriggering a kernel panic / use-after-free.\n\nSwitch from timer_delete_sync() to timer_shutdown_sync(). This guarantees\nthat any in-flight timer handler has finished and prevents subsequent\nre-arming attempts from running workers from succeeding. When monitoring\nis restarted later, timer_setup() is invoked, which cleanly\nre-initializes the timer."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:16:57.641Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/bda4d9525fb91a2388ee09669421b8d505290864"
        },
        {
          "url": "https://git.kernel.org/stable/c/c391a40f71886b28c082b47270f0e856fa3e1150"
        }
      ],
      "title": "drop_monitor: use timer_shutdown_sync() to prevent timer rearming during teardown",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98286",
    "datePublished": "2026-10-06T08:45:47.167Z",
    "dateReserved": "2026-09-25T10:25:14.335Z",
    "dateUpdated": "2026-10-19T09:16:57.641Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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