CVE-2019-19079 in Linux
Summary
by MITRE • 01/25/2023
A memory leak in the qrtr_tun_write_iter() function in net/qrtr/tun.c in the Linux kernel before 5.3 allows attackers to cause a denial of service (memory consumption), aka CID-a21b7f0cff19.
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Analysis
by VulDB Data Team • 02/23/2024
The vulnerability identified as CVE-2019-19079 represents a critical memory management flaw within the Linux kernel's Qualcomm Remote processor (qrtr) subsystem. This issue specifically affects the qrtr_tun_write_iter() function located in the net/qrtr/tun.c source file, which handles communication between user-space applications and the kernel's qrtr networking stack. The vulnerability manifests as a memory leak that occurs during the processing of network packets through the qrtr tunnel interface, creating a persistent resource exhaustion condition that can be exploited by malicious actors. The flaw exists in kernel versions prior to 5.3, making a significant portion of deployed systems vulnerable to this memory consumption attack vector.
The technical root cause of this vulnerability stems from improper memory management within the qrtr_tun_write_iter() function where allocated memory buffers are not correctly freed upon completion of packet processing operations. This memory leak occurs when the function handles write operations to the qrtr tunnel device, specifically during the iteration process where data is transferred from user space to kernel space. The flaw allows attackers to repeatedly send crafted packets through the qrtr interface, causing the kernel to continuously allocate memory without proper deallocation, leading to progressive memory consumption. This behavior directly violates the principles of memory resource management and can be classified as a CWE-401: Improper Release of Memory Before Removal from Resource Pool.
The operational impact of CVE-2019-19079 extends beyond simple resource exhaustion, creating a substantial denial of service condition that can severely compromise system stability and availability. When exploited, the vulnerability allows attackers to consume system memory at an accelerated rate, potentially leading to system crashes, application failures, or complete system hang conditions. The attack can be executed remotely through the qrtr network interface, making it particularly dangerous in environments where such interfaces are exposed to untrusted network traffic. This vulnerability is particularly concerning in embedded systems and mobile devices that rely heavily on the qrtr subsystem for communication with remote processors, as these platforms often have limited memory resources and may be less likely to receive timely security updates. The ATT&CK framework categorizes this as a resource exhaustion technique under the T1499.004 sub-technique, where adversaries leverage system vulnerabilities to consume computational resources.
Mitigation strategies for CVE-2019-19079 focus primarily on upgrading to kernel versions 5.3 or later where the memory leak has been addressed through proper memory management implementation. System administrators should prioritize patching affected systems, particularly in production environments where qrtr interfaces are active. Additionally, implementing network segmentation and access controls to limit exposure of qrtr interfaces to trusted sources can provide defense-in-depth protection. Monitoring for unusual memory consumption patterns and implementing automated alerting for memory usage thresholds can help detect exploitation attempts. The vulnerability demonstrates the critical importance of proper memory management in kernel space operations and highlights the need for comprehensive security testing of network subsystems. Organizations should also consider implementing intrusion detection systems that can monitor for anomalous qrtr traffic patterns that might indicate exploitation attempts, as the memory leak behavior creates distinctive network and system performance signatures that can be detected through proper monitoring protocols.