Linux Kernel IPMI Subsystem Memory Leak Vulnerability in SMI Initialization

A memory leak vulnerability has been identified in the Linux kernel's IPMI subsystem, specifically within the 'try_smi_init' function of the IPMI Serial Interface (SI) driver. This vulnerability affects several versions of the Linux kernel, including 4.19 and later. The issue arises when an error occurs before the SMI handlers are registered, after the 'si_sm' variable has been allocated. In such cases, the allocated memory is not freed, leading to a memory leak. The kernel's memory leak detector (kmemleak) reported this unreferenced object as a leak, indicating that the memory was not properly released after it was no longer needed.

Impact

Exploitation of this vulnerability leads to a memory leak, where allocated memory is not properly freed, potentially causing increased memory usage and degradation of system performance over time.

Reproduction

The vulnerability can be reproduced by loading a kernel module that initializes the IPMI SMI interface. If the initialization process encounters an error before the SMI handlers are registered, the 'si_sm' variable will remain allocated but unreferenced, causing a memory leak. This scenario can be simulated by introducing an error in the initialization process after the memory allocation but before the handler registration.

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 kernel documentation.