Linux Kernel DAMON Sysfs Directory Cleanup Vulnerability

A vulnerability exists in the Linux kernel's DAMON (Data Access Monitoring) subsystem related to the management of sysfs directories. When the setup of a DAMOS-scheme DAMON sysfs directory fails after the access_pattern directory has been created, the subdirectories within access_pattern are not properly cleaned up. This oversight leads to a nearly non-functional DAMON sysfs interface, which remains broken until the system is rebooted. Additionally, the failure to remove these directories causes a memory leak. The issue has been addressed by implementing a cleanup process for the directories in such failure scenarios.

Impact

The improper handling of directory cleanup can cause the DAMON sysfs interface to malfunction, leading to a broken state that persists until a system reboot. This issue also results in a memory leak due to the unremoved directories.

Reproduction

To reproduce this vulnerability, create a DAMOS-scheme DAMON sysfs directory and intentionally cause the setup process to fail after the access_pattern directory has been established. This will result in the subdirectories of access_pattern not being cleaned up, leaving the DAMON sysfs interface in a compromised state and causing a memory leak.

Remediation

Users can upgrade to the latest version of the Linux kernel where this vulnerability has been addressed. Instructions for upgrading the Linux kernel can be found in the official Linux documentation.