{"id":"CVE-2026-98286","state":"PUBLISHED","title":"drop_monitor: use timer_shutdown_sync() to prevent timer rearming during teardown","description":"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(&data->send_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.","publishedAt":"2026-10-06T08:45:47.167Z","updatedAt":"2026-10-19T09:16:57.641Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"9398e9c0b1d44eeb700e9e766c02bcc765c82570","status":"affected","lessThan":"9616b0c67fbd8cc0b49de7b26cdf2ab33747c80e","versionType":"git"},{"version":"9398e9c0b1d44eeb700e9e766c02bcc765c82570","status":"affected","lessThan":"bda4d9525fb91a2388ee09669421b8d505290864","versionType":"git"},{"version":"9398e9c0b1d44eeb700e9e766c02bcc765c82570","status":"affected","lessThan":"c391a40f71886b28c082b47270f0e856fa3e1150","versionType":"git"},{"version":"2514c7ad115e762562c7bdd58bb1ab3425a98245","status":"affected","versionType":"git"},{"version":"439b1164da3612ec7e186e1dc314471e7190bfc7","status":"affected","versionType":"git"},{"version":"5.10.27","status":"affected","lessThan":"5.11","versionType":"semver"},{"version":"5.11.11","status":"affected","lessThan":"5.12","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/core/drop_monitor.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.12","versionType":"semver"},{"version":"6.18.54","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.8","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/core/drop_monitor.c"]}],"references":["https://git.kernel.org/stable/c/9616b0c67fbd8cc0b49de7b26cdf2ab33747c80e","https://git.kernel.org/stable/c/bda4d9525fb91a2388ee09669421b8d505290864","https://git.kernel.org/stable/c/c391a40f71886b28c082b47270f0e856fa3e1150"],"weaknesses":[],"ingestedAt":"2026-10-29T20:13:43.249Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/98xxx/CVE-2026-98286.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-98286","state":"PUBLISHED","datePublished":"2026-10-06T08:45:47.167Z","dateUpdated":"2026-10-19T09:16:57.641Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-09-25T10:25:14.335Z"},"containers":{"cna":{"title":"drop_monitor: use timer_shutdown_sync() to prevent timer rearming during teardown","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(&data->send_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."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"9398e9c0b1d44eeb700e9e766c02bcc765c82570","status":"affected","lessThan":"9616b0c67fbd8cc0b49de7b26cdf2ab33747c80e","versionType":"git"},{"version":"9398e9c0b1d44eeb700e9e766c02bcc765c82570","status":"affected","lessThan":"bda4d9525fb91a2388ee09669421b8d505290864","versionType":"git"},{"version":"9398e9c0b1d44eeb700e9e766c02bcc765c82570","status":"affected","lessThan":"c391a40f71886b28c082b47270f0e856fa3e1150","versionType":"git"},{"version":"2514c7ad115e762562c7bdd58bb1ab3425a98245","status":"affected","versionType":"git"},{"version":"439b1164da3612ec7e186e1dc314471e7190bfc7","status":"affected","versionType":"git"},{"version":"5.10.27","status":"affected","lessThan":"5.11","versionType":"semver"},{"version":"5.11.11","status":"affected","lessThan":"5.12","versionType":"semver"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/core/drop_monitor.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.12","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.12","versionType":"semver"},{"version":"6.18.54","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.2.8","status":"unaffected","lessThanOrEqual":"7.2.*","versionType":"semver"},{"version":"7.3","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/core/drop_monitor.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/9616b0c67fbd8cc0b49de7b26cdf2ab33747c80e"},{"url":"https://git.kernel.org/stable/c/bda4d9525fb91a2388ee09669421b8d505290864"},{"url":"https://git.kernel.org/stable/c/c391a40f71886b28c082b47270f0e856fa3e1150"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-19T09:16:57.641Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"6.18.54"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"7.2.8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.12","versionEndExcluding":"7.3"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.10.27"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.11.11"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}