CVE-2019-15916 in Linux
Summary
by MITRE • 01/25/2023
An issue was discovered in the Linux kernel before 5.0.1. There is a memory leak in register_queue_kobjects() in net/core/net-sysfs.c, which will cause denial of service.
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Analysis
by VulDB Data Team • 10/14/2024
The vulnerability identified as CVE-2019-15916 represents a critical memory management flaw within the Linux kernel's networking subsystem that affects versions prior to 5.0.1. This issue manifests in the register_queue_kobjects() function located within the net/core/net-sysfs.c source file, demonstrating how seemingly minor implementation details can lead to significant system stability concerns. The flaw specifically targets the kernel's handling of network queue kobjects, which are part of the kernel's sysfs interface that exposes network device information and configuration parameters to user space. When this function processes network queue registrations, it fails to properly release allocated memory resources, creating a gradual accumulation of unreleased memory blocks that eventually depletes available system memory.
The technical nature of this vulnerability aligns with CWE-401, which categorizes memory leaks as a fundamental weakness in software design where allocated memory is not properly deallocated, leading to resource exhaustion. This particular implementation flaw occurs during the dynamic registration of network queue objects within the kernel's sysfs framework, where the kernel maintains a mapping between network device queues and their corresponding sysfs entries. The memory leak is not a one-time occurrence but rather a progressive degradation that occurs each time network queue kobjects are registered, making the vulnerability particularly insidious as it can remain dormant for extended periods before manifesting as a denial of service condition. The affected code path is typically triggered when network devices are created or reconfigured, particularly in scenarios involving high-frequency network queue operations or when multiple network interfaces are dynamically managed.
The operational impact of this vulnerability extends beyond simple resource consumption to potentially compromise entire system availability, as the progressive memory exhaustion can lead to system instability, application crashes, or complete system lockups. Network administrators and system operators may observe gradual performance degradation over time, with system memory becoming increasingly constrained until the kernel can no longer allocate necessary resources for network operations or other kernel functions. This vulnerability is particularly concerning in server environments where continuous network traffic and frequent network interface management occur, as the memory leak compounds over time and can be exploited to create sustained denial of service conditions. The attack surface is broad as any process that interacts with network queue management or triggers the registration of kobjects through the sysfs interface can contribute to the memory leak accumulation.
Mitigation strategies for CVE-2019-15916 focus primarily on kernel version upgrades to 5.0.1 or later, where the memory leak has been addressed through proper resource management in the register_queue_kobjects() function. System administrators should prioritize patching affected systems, particularly in production environments where network stability is critical. Additionally, monitoring system memory usage and implementing automated alerts for memory consumption patterns can help detect early signs of the vulnerability's manifestation. The fix implemented in kernel version 5.0.1 addresses the root cause by ensuring proper cleanup of allocated memory structures when kobjects are registered, following established kernel memory management practices and principles of resource lifecycle management. Organizations should also consider implementing network traffic monitoring to detect unusual patterns that might indicate the vulnerability's exploitation, as the memory leak can be observed through gradual increases in system memory usage that correlate with network queue operations. This vulnerability demonstrates the importance of proper resource management in kernel space and aligns with ATT&CK technique T1499, which covers resource exhaustion attacks that can be leveraged to cause system instability or denial of service conditions through memory management flaws.