Linux Kernel cpufreq Governor Kobject Memory Management Vulnerability

A vulnerability in the Linux kernel's cpufreq governor related to improper memory management of kobjects has been addressed. The issue arose because the dbs_data structure, which includes a gov_attr_set that embeds a kobject, was not being freed correctly. Kobjects require a specific release method, and the standard kfree function could not be used to deallocate them directly. To resolve this, the cpufreq_dbs_data_release function was introduced to properly release the dbs_data via the kobject release method. This change prevents potential memory management warnings and call trace issues related to improperly freed objects.

Impact

The vulnerability could lead to memory management errors, such as warnings about objects not being freed correctly, which can cause debugging complications and potentially allow for memory corruption issues.

Reproduction

The vulnerability can be reproduced by using the cpufreq_dbs governor on a Marvell OcteonTX CN96XX board running a Linux kernel version that includes the vulnerability. After setting the governor, the exit callback of the governor can be invoked, which will trigger the improper handling of the kobject, leading to the debug warning about the object not being freed correctly.

Remediation

Users should upgrade to a patched version of the Linux kernel where this vulnerability has been addressed.