CVE-2022-49403 in Linux
Summary
by MITRE • 02/26/2025
In the Linux kernel, the following vulnerability has been resolved:
lib/string_helpers: fix not adding strarray to device's resource list
Add allocated strarray to device's resource list. This is a must to automatically release strarray when the device disappears.
Without this fix we have a memory leak in the few drivers which use devm_kasprintf_strarray().
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Analysis
by VulDB Data Team • 02/26/2025
The vulnerability described in CVE-2022-49403 resides within the Linux kernel's device management subsystem, specifically affecting how string arrays are handled during device resource allocation. This issue impacts the proper cleanup of dynamically allocated memory structures when devices are removed from the system. The root cause lies in the string_helpers library component which is responsible for managing string array allocations in kernel space. When drivers utilize the devm_kasprintf_strarray() function to allocate string arrays for device-specific operations, the allocated memory structures are not properly registered with the device's resource management list.
The technical flaw manifests as a missing registration step in the device resource management system. The devm_kasprintf_strarray() function allocates memory for string arrays but fails to add these allocations to the device's resource list that tracks all memory allocations associated with a specific device. This omission prevents the automatic cleanup mechanism from recognizing and releasing the allocated string arrays when the device is removed or destroyed. The vulnerability directly relates to improper resource management practices that violate fundamental kernel memory management principles and can lead to systematic memory leakage across multiple drivers that depend on this functionality.
The operational impact of this vulnerability extends beyond simple memory consumption issues to potentially destabilize system performance and reliability. When multiple devices are repeatedly added and removed from the system, or when drivers that utilize devm_kasprintf_strarray() are frequently loaded and unloaded, the cumulative effect of unreleased memory can lead to significant memory fragmentation and eventual system resource exhaustion. This memory leak affects the broader kernel subsystems that depend on proper device resource management, potentially causing system instability, reduced performance, and in extreme cases, system crashes or lockups. The vulnerability affects drivers that rely on automatic resource cleanup mechanisms, making it particularly concerning for embedded systems and server environments where device hot-plugging and dynamic driver loading are common practices.
Mitigation strategies for this vulnerability require kernel updates that implement the proper registration of string arrays with device resource lists. The fix involves modifying the string_helpers library to ensure that any allocated string arrays are automatically added to the device's resource management list during allocation. This approach aligns with the established kernel development practices for resource management and follows the principle of automatic cleanup through reference counting and device lifecycle management. System administrators should prioritize applying kernel patches that address this issue, particularly in production environments where device management and memory efficiency are critical. The vulnerability demonstrates the importance of proper resource tracking in kernel space and highlights the potential consequences of neglecting automatic cleanup mechanisms, which is consistent with common patterns observed in memory management vulnerabilities classified under CWE-401 as improper resource management.
This vulnerability also relates to broader security implications within the kernel's memory management subsystem, where improper resource handling can create potential attack vectors. While the immediate impact is a memory leak rather than a direct security exploit, the underlying issue represents poor resource management practices that could potentially be leveraged in denial-of-service scenarios. The fix addresses the core problem by ensuring that all device-specific allocations are properly tracked and cleaned up, which aligns with the ATT&CK framework's approach to kernel-level resource management and system stability. The resolution demonstrates the importance of comprehensive testing for resource management functions and proper integration with existing kernel subsystems to prevent unintended memory leakage patterns that could compromise system reliability and performance over time.