CVE-2022-48856 in Linux
Summary
by MITRE • 07/16/2024
In the Linux kernel, the following vulnerability has been resolved:
gianfar: ethtool: Fix refcount leak in gfar_get_ts_info
The of_find_compatible_node() function returns a node pointer with refcount incremented, We should use of_node_put() on it when done Add the missing of_node_put() to release the refcount.
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Analysis
by VulDB Data Team • 07/23/2024
The vulnerability CVE-2022-48856 represents a memory management issue within the Linux kernel's gianfar network driver implementation. This flaw specifically affects the ethtool interface functionality of the gianfar driver which is commonly used for managing ethernet devices in embedded systems and industrial networking applications. The vulnerability arises from improper handling of device tree node references during timestamp information retrieval operations, creating a potential memory leak condition that could degrade system performance over time.
The technical root cause of this vulnerability lies in the improper reference counting management of device tree nodes within the gianfar_get_ts_info function. When the of_find_compatible_node() function is invoked, it returns a node pointer with an incremented reference count to maintain proper resource management. However, the code fails to properly decrement this reference count through the required of_node_put() call when the node pointer is no longer needed. This reference count leak prevents the kernel's memory management subsystem from properly releasing the associated device tree node resources, leading to gradual memory consumption that could eventually impact system stability.
This vulnerability impacts systems utilizing the gianfar network driver, particularly those in industrial automation, embedded networking, and real-time control environments where continuous operation is critical. The operational impact manifests as progressive memory consumption that may lead to system slowdowns, reduced available memory for other processes, and potentially system instability or crashes. The vulnerability is particularly concerning in embedded systems where memory resources are limited and system uptime is essential for operational continuity. Network administrators and system integrators managing industrial control systems, network infrastructure equipment, or embedded devices using gianfar drivers should be aware of this issue as it could compromise system reliability in mission-critical deployments.
The fix for CVE-2022-48856 involves adding the missing of_node_put() call to properly release the reference count on the device tree node pointer returned by of_find_compatible_node(). This simple but critical change ensures that all acquired references are properly released, allowing the kernel's memory management subsystem to reclaim the resources. The solution aligns with standard Linux kernel development practices and follows the established pattern for managing device tree node references throughout the kernel codebase. This remediation addresses the core issue identified in the vulnerability while maintaining all existing functionality of the gianfar driver's ethtool interface.
The vulnerability classifies under CWE-404, which specifically addresses improper resource management or resource leaks in software systems. The issue also relates to the broader category of memory management flaws that can lead to system instability and performance degradation. From an attack perspective, while this vulnerability does not directly enable privilege escalation or remote code execution, it represents a significant reliability concern that could be exploited to cause denial-of-service conditions in systems where continuous operation is critical. The vulnerability aligns with ATT&CK technique T1499.004, which covers resource exhaustion attacks through memory leaks, making it a potential vector for system degradation attacks in embedded and industrial environments where resource constraints are common.