CVE-2019-19073 in Linux
Summary
by MITRE
Memory leaks in drivers/net/wireless/ath/ath9k/htc_hst.c in the Linux kernel through 5.3.11 allow attackers to cause a denial of service (memory consumption) by triggering wait_for_completion_timeout() failures. This affects the htc_config_pipe_credits() function, the htc_setup_complete() function, and the htc_connect_service() function, aka CID-853acf7caf10.
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Analysis
by VulDB Data Team • 02/23/2024
The vulnerability described in CVE-2019-19073 represents a critical memory management flaw within the Linux kernel's wireless networking subsystem, specifically within the ath9k driver for Atheros wireless chipsets. This issue manifests as memory leaks that occur during the initialization and configuration phases of wireless communication, affecting systems running kernel versions through 5.3.11. The flaw resides in the HTC (Host Target Communication) layer that facilitates communication between the host system and wireless chipsets, making it particularly dangerous for devices that rely heavily on wireless connectivity.
The technical implementation of this vulnerability stems from improper memory deallocation within three key functions: htc_config_pipe_credits(), htc_setup_complete(), and htc_connect_service(). When these functions encounter failures during wait_for_completion_timeout() operations, they fail to properly release allocated memory resources, leading to gradual memory consumption over time. This memory leak pattern is particularly insidious because it occurs during normal operational procedures rather than as a result of malicious input, making it difficult to detect and exploit systematically. The CWE-401 classification applies here as this represents a classic memory leak vulnerability where allocated memory is not properly freed, creating a resource exhaustion condition.
The operational impact of this vulnerability extends beyond simple system slowdowns to potentially cause complete system instability or denial of service conditions. Attackers can trigger these memory leaks by repeatedly initiating wireless connection attempts or by manipulating the HTC communication layer to force the failure conditions that prevent proper memory cleanup. Systems running affected kernel versions may experience progressive memory consumption that eventually leads to system crashes, application failures, or complete system lockups, particularly in environments where wireless connectivity is frequently established and terminated. This vulnerability affects a broad range of devices including laptops, servers, and embedded systems that utilize Atheros wireless chipsets, making it a widespread concern across multiple computing environments.
Mitigation strategies for CVE-2019-19073 should prioritize immediate kernel updates to versions that contain the patched HTC driver code, as this represents the most effective solution to address the root cause of the memory leak. System administrators should implement monitoring solutions to track memory usage patterns on affected systems, particularly during periods of high wireless activity, to detect early signs of memory exhaustion. Additionally, implementing resource limits and memory watchdog mechanisms can help contain the impact of memory leaks by preventing them from consuming all available system resources. Organizations should also consider implementing network segmentation and access controls to limit the potential attack surface, as outlined in the ATT&CK framework's defense-in-depth strategies. The vulnerability demonstrates the importance of proper resource management in kernel space code and highlights the need for comprehensive testing of error handling paths in device drivers to prevent similar issues from occurring in future implementations.