Executive brief
The Linux kernel's devfreq power management subsystem fails to properly clean up memory allocated during device initialization, causing a memory leak when devices are released. This leak reduces available system memory over time, potentially degrading system performance or causing out-of-memory conditions on memory-constrained embedded systems.
Technical details
A resource leak exists in the devfreq device release function (devfreq_dev_release) in drivers/devfreq/devfreq.c. The function calls srcu_init_notifier_head() during device initialization, which allocates internal data structures, but fails to invoke the corresponding cleanup function srcu_cleanup_notifier_head() during device release. This causes allocated memory to be lost each time a devfreq device is released. The vulnerability is fixed by adding a single srcu_cleanup_notifier_head() call in the device release path. The leak is detectable via kernel memory leak detection tools (kmemleak). This affects the power management and dynamic frequency scaling subsystem used by device drivers.
Affected products
- Linux Linux kernel versions prior to patch commit 5693d077595de721f9ddbf9d37f40e5409707dfe
Timeline
- 2023-08-09: disclosed
- 2023-09-13: patched