CVE-2022-49653 in Linux
Summary
by MITRE • 02/26/2025
In the Linux kernel, the following vulnerability has been resolved:
i2c: piix4: Fix a memory leak in the EFCH MMIO support
The recently added support for EFCH MMIO regions introduced a memory leak in that code path. The leak is caused by the fact that release_resource() merely removes the resource from the tree but does not free its memory. We need to call release_mem_region() instead, which does free the memory. As a nice side effect, this brings back some symmetry between the legacy and MMIO paths.
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Analysis
by VulDB Data Team • 02/26/2025
The vulnerability CVE-2022-49653 represents a memory leak issue within the Linux kernel's i2c piix4 driver implementation that specifically affects the EFCH MMIO (Memory-Mapped I/O) support functionality. This flaw was introduced during the implementation of new MMIO region handling capabilities and demonstrates a critical oversight in resource management practices within kernel space code. The vulnerability exists in the i2c subsystem where the piix4 driver handles communication with certain Intel chipsets, particularly those requiring EFCH (Enhanced Feature Control Handler) MMIO support for proper operation. The issue manifests when the kernel attempts to release memory regions that have been allocated for MMIO operations, creating a persistent memory consumption problem that can accumulate over time and potentially lead to system instability.
The technical root cause of this vulnerability stems from improper resource deallocation mechanisms within the kernel's memory management subsystem. When the release_resource() function is called to remove a memory region from the resource tree, it fails to actually free the underlying memory allocation, leaving the memory in a leaked state. This specific function call pattern violates fundamental kernel memory management principles and creates a classic memory leak scenario where allocated resources are not properly returned to the system. The flaw is particularly significant because it affects the EFCH MMIO support path, which is a specialized code path designed for handling enhanced feature control operations in certain Intel chipsets. The issue demonstrates a lack of proper resource cleanup implementation where developers failed to recognize that release_resource() and release_mem_region() serve different purposes in the kernel's memory management hierarchy, with the latter being specifically designed to free memory allocations.
The operational impact of CVE-2022-49653 extends beyond simple memory consumption issues to potentially affect system stability and performance over extended periods of operation. While the immediate effect may appear as gradual memory bloat, the cumulative effect of multiple leaked memory regions can lead to memory exhaustion conditions that impact system responsiveness and overall performance. In embedded systems or servers running continuously, this memory leak could eventually contribute to system crashes or require forced reboots to clear the accumulated memory consumption. The vulnerability particularly affects systems utilizing Intel chipsets that require EFCH MMIO support for i2c communication, making it relevant to a specific but significant subset of Linux installations including servers, embedded devices, and desktop systems using affected hardware configurations. This type of vulnerability falls under CWE-401: "Improper Release of Memory Before Removing Last Reference" and represents a classic example of resource management failure in kernel code that can have cascading effects on system reliability.
Mitigation strategies for CVE-2022-49653 involve applying the official kernel patch that corrects the resource deallocation mechanism by replacing release_resource() with release_mem_region() in the affected code path. System administrators should prioritize updating their Linux kernel installations to versions containing the fix, typically found in kernel releases 5.19 and later. The fix restores proper symmetry between legacy and MMIO code paths while ensuring that memory allocations are properly freed when resources are released. Organizations should implement comprehensive patch management procedures to ensure all systems utilizing i2c piix4 drivers with EFCH MMIO support receive the necessary updates. Monitoring for memory consumption patterns on systems running vulnerable kernel versions can help identify potential impacts before they escalate into more serious operational issues. Additionally, this vulnerability highlights the importance of thorough testing of new kernel features, particularly those involving memory management and resource allocation, to prevent similar issues from arising in production environments. The ATT&CK framework categorizes this issue under T1070.004: "Indicator Removal on Host: File Deletion" and T1484.001: "Privilege Escalation: Group Policy Modification" in the context of maintaining system integrity and resource availability, though the primary concern remains the memory management aspect rather than direct privilege escalation.