CVE-2022-49866 in Linux
Summary
by MITRE • 05/01/2025
In the Linux kernel, the following vulnerability has been resolved:
net: wwan: mhi: fix memory leak in mhi_mbim_dellink
MHI driver registers network device without setting the needs_free_netdev flag, and does NOT call free_netdev() when unregisters network device, which causes a memory leak.
This patch sets needs_free_netdev to true when registers network device, which makes netdev subsystem call free_netdev() automatically after unregister_netdevice().
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Analysis
by VulDB Data Team • 10/01/2025
The vulnerability identified as CVE-2022-49866 represents a critical memory management flaw within the Linux kernel's Mobile Industry Association (MHI) driver subsystem, specifically affecting WWAN (Wireless Wide Area Network) communication capabilities. This issue resides in the mhi_mbim_dellink function where improper network device cleanup procedures lead to persistent memory allocation failures. The MHI driver serves as a crucial interface for mobile communication devices, facilitating data transmission between mobile network adapters and the host system through standardized protocols. When network devices are registered through the MHI subsystem without proper memory management flags, the kernel's networking subsystem fails to automatically reclaim allocated memory resources during device removal operations, creating a persistent memory leak that can accumulate over time and potentially impact system stability.
The technical root cause of this vulnerability stems from the improper initialization of network device structures within the MHI driver's MBIM (Mobile Broadband Interface Model) implementation. During the device registration process, the driver fails to set the needs_free_netdev flag to true, which is a critical parameter that signals to the kernel's networking subsystem that automatic memory cleanup is required upon device removal. This flag serves as a fundamental mechanism for the netdev subsystem to determine whether it should automatically invoke the free_netdev() function during the unregister_netdevice() operation. Without this flag, the kernel maintains references to allocated memory structures even after the network device has been logically removed from the system, resulting in a memory leak that grows proportionally with the number of device registration and deregistration cycles. The flaw directly violates standard kernel memory management practices and represents a clear deviation from established protocols for device lifecycle management.
The operational impact of this memory leak vulnerability extends beyond simple resource consumption, potentially leading to system instability and performance degradation in environments where WWAN devices experience frequent connection and disconnection cycles. Mobile communication systems, particularly those utilizing 5G and LTE networks, often require dynamic network device management through frequent reconfiguration operations, making this vulnerability particularly dangerous in mobile and embedded systems. The cumulative effect of memory leaks can result in system memory exhaustion, forcing the kernel to employ aggressive memory management strategies that may impact overall system performance or even cause system crashes. In resource-constrained environments such as mobile devices, IoT systems, or embedded communication appliances, this memory leak could significantly reduce operational lifetime and reliability. The vulnerability affects systems running Linux kernel versions where the MHI driver is implemented, particularly those supporting mobile broadband connectivity through WWAN interfaces, making it relevant to a broad range of mobile communication devices and network infrastructure equipment.
Mitigation strategies for CVE-2022-49866 focus on implementing the recommended patch that properly sets the needs_free_netdev flag during network device registration. This solution aligns with established kernel development practices and security guidelines for memory management within the networking subsystem. System administrators should prioritize updating their Linux kernel versions to include the patched implementation, particularly in environments where mobile broadband connectivity is heavily utilized. The fix represents a straightforward code modification that ensures proper automatic memory cleanup through the existing kernel infrastructure rather than requiring complex workaround solutions. Organizations maintaining mobile communication infrastructure should conduct comprehensive testing to ensure that the patch does not introduce regressions in network functionality or device compatibility. Additionally, monitoring systems should be implemented to track memory usage patterns and identify potential memory leak accumulation in environments where the vulnerability might persist. This vulnerability demonstrates the importance of proper kernel driver development practices and adherence to established memory management protocols, with implications extending to the broader security community's understanding of kernel-level memory corruption vulnerabilities and their potential impact on system stability and resource availability.