drop_monitor: use timer_shutdown_sync() to prevent timer rearming during teardown
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 5.11, 5.12, 6.18.54, 7.2.8
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
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.
Timeline
- CVE published
- Record last updated
Affected versions
- Linux Linux
From 9398e9c0b1d44eeb700e9e766c02bcc765c82570 · fixed in 9616b0c67fbd8cc0b49de7b26cdf2ab33747c80e; From 9398e9c0b1d44eeb700e9e766c02bcc765c82570 · fixed in bda4d9525fb91a2388ee09669421b8d505290864; From 9398e9c0b1d44eeb700e9e766c02bcc765c82570 · fixed in c391a40f71886b28c082b47270f0e856fa3e1150; From 5.10.27 · fixed in 5.11; From 5.11.11 · fixed in 5.12
- Linux Linux
5.12
- KernelLinux
From 5.12.0 · fixed in 6.18.54; From 6.19.0 · fixed in 7.2.8