Linux Kernel USB ULPI Debugfs Memory Leak Vulnerability

A memory leak vulnerability has been identified in the Linux kernel's USB ULPI (UTMI+ Low Pin Count) driver. The issue arises when the function 'debugfs_lookup()' is called without subsequently releasing the reference with 'dput()'. This oversight can lead to a gradual accumulation of unreleased memory. The vulnerability affects the stable versions of the Linux kernel.

Impact

The vulnerability causes a memory leak, where allocated memory is not properly released, potentially leading to increased memory usage over time and causing performance degradation or exhaustion of system resources.

Reproduction

The vulnerability can be reproduced by loading a USB ULPI driver that uses 'debugfs_lookup()' to access debugfs entries. If the retrieved entry is not properly released with 'dput()', the memory leak will occur. This can be observed by monitoring the system's memory usage over time, which will show an increase due to the unreleased references.

Remediation

The vulnerability has been addressed by modifying the ULPI driver to use 'debugfs_lookup_and_remove()', which automatically handles the reference management and prevents the memory leak. Users should upgrade to the patched version of the Linux kernel available in the Linux kernel stable tree.