Linux Kernel Hotplug Callback Leak Vulnerability in ARM DMC-620 PMU Driver

A hotplug callback leak vulnerability has been identified in the Linux kernel's ARM DMC-620 performance monitoring unit (PMU) driver. The issue arises in the 'dmc620_pmu_init()' function, which fails to remove a callback added by 'cpuhp_setup_state_multi()' when 'platform_driver_register()' encounters an error. This oversight can lead to a callback leak, similar to a previously addressed issue in the ARM CCN driver. The vulnerability affects the Linux kernel stable tree.

Impact

The vulnerability can cause a hotplug callback leak, where callbacks are not properly removed, potentially leading to undefined behavior or resource management issues.

Reproduction

The vulnerability can be reproduced by initializing the ARM DMC-620 PMU driver and simulating a failure in the 'platform_driver_register()' function. This will cause the 'dmc620_pmu_init()' function to exit without removing the hotplug callback, creating a leak.

Remediation

Users can apply the latest patches available in the Linux kernel stable tree to address this vulnerability.