Executive brief
The Linux kernel's clock notifier registration function (devm_clk_notifier_register) contains a memory leak where allocated resources are not properly registered with the device manager, preventing automatic cleanup when devices are detached. This can lead to gradual memory exhaustion on systems that repeatedly attach and detach devices or register and unregister clock notifiers, particularly in embedded or mobile environments.
Technical details
The vulnerability is a resource management bug in drivers/clk/clk.c where devm_clk_notifier_register() allocates a device resource (devres) for managing clock notifier callbacks but fails to register it with the device using devres_add(). This omission prevents the kernel's device resource management infrastructure from properly tracking and cleaning up the notifier on device detachment, resulting in a memory leak. The bug affects all kernel versions since the function was introduced (commit 6d30d50d037d). The fix is trivial—adding a single devres_add() call after successful initialization—and has been patched in stable kernel branches.
Affected products
- Linux Linux kernel All versions since 6d30d50d037d
Timeline
- 2023-06-20: disclosed
- 2023-07-19: patched