CVE-2022-49665 in Linux
Summary
by MITRE • 02/26/2025
In the Linux kernel, the following vulnerability has been resolved:
platform/x86: thinkpad_acpi: Fix a memory leak of EFCH MMIO resource
Unlike release_mem_region(), a call to release_resource() does not free the resource, so it has to be freed explicitly to avoid a memory leak.
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Analysis
by VulDB Data Team • 10/23/2025
The vulnerability identified as CVE-2022-49665 resides within the Linux kernel's thinkpad_acpi subsystem, specifically affecting the platform/x86 component responsible for managing ThinkPad laptop hardware functionalities. This memory leak occurs in the context of Extended Feature Control Handler (EFCH) MMIO resource management, where the kernel fails to properly release allocated memory resources during device cleanup operations. The issue manifests when the system attempts to release resources associated with ThinkPad ACPI hardware controls, creating a persistent memory allocation that cannot be reclaimed by the system's memory management subsystem.
The technical flaw stems from an improper resource management pattern within the kernel's memory allocation routines. When the release_resource() function is called, it differs fundamentally from release_mem_region() in that it does not automatically free the underlying memory resource structure. Instead, release_resource() only removes the resource from the resource tree structure, leaving the actual memory allocation intact. This creates a memory leak scenario where the resource structure remains allocated in kernel memory, consuming system resources without being freed. The flaw is particularly significant because it operates at the kernel level where memory management efficiency directly impacts system stability and performance.
The operational impact of this vulnerability extends beyond simple memory consumption issues to potentially compromise system stability and resource availability. As the memory leak accumulates over time, it can lead to progressive memory exhaustion, particularly on systems with multiple ThinkPad devices or those running for extended periods. This degradation affects not only the affected system's performance but could also contribute to system instability, especially in embedded systems or servers where memory resources are constrained. The vulnerability is particularly concerning for enterprise environments where multiple ThinkPad laptops might be connected to a system or when the kernel is running in resource-constrained environments.
Mitigation strategies for CVE-2022-49665 focus on ensuring proper resource cleanup through explicit memory deallocation. The fix implemented in the kernel requires that developers explicitly call the kfree() function or equivalent memory deallocation routines to free the resource structure after release_resource() is invoked. This approach aligns with the common practices outlined in the Common Weakness Enumeration (CWE) category CWE-401, which addresses improper resource management and memory leaks. From an ATT&CK framework perspective, this vulnerability relates to privilege escalation and system stability compromise, as it can be leveraged to exhaust system resources and potentially impact other processes. Organizations should prioritize applying the kernel patch that implements the proper resource management pattern, ensuring that all affected ThinkPad systems receive the update. Additionally, system monitoring should include tracking memory usage patterns to detect potential memory leak impacts, particularly in environments with high system uptime or multiple concurrent ThinkPad devices. The fix demonstrates the importance of careful resource management in kernel code, where improper memory handling can lead to systemic stability issues that affect the entire computing environment.