CVE-2018-6554 in Linux
Summary
by MITRE
Memory leak in the irda_bind function in net/irda/af_irda.c and later in drivers/staging/irda/net/af_irda.c in the Linux kernel before 4.17 allows local users to cause a denial of service (memory consumption) by repeatedly binding an AF_IRDA socket.
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Analysis
by VulDB Data Team • 05/07/2023
The vulnerability described in CVE-2018-6554 represents a critical memory management flaw within the Linux kernel's infrared (IrDA) protocol implementation that affects systems running kernel versions prior to 4.17. This memory leak occurs specifically within the irda_bind function located in the net/irda/af_irda.c file and subsequently in the drivers/staging/irda/net/af_irda.c file, demonstrating a persistent issue in the kernel's handling of IrDA socket operations. The flaw stems from inadequate memory cleanup procedures during socket binding operations, creating a condition where allocated memory resources are not properly released back to the system's memory pool.
The technical nature of this vulnerability aligns with CWE-401, which identifies improper handling of memory allocation and deallocation as a fundamental weakness in software systems. When local users repeatedly execute the irda_bind function on AF_IRDA sockets, the kernel fails to properly deallocate previously allocated memory structures, resulting in progressive memory consumption that gradually depletes available system resources. This particular flaw operates at the kernel level, meaning that malicious users with local access can exploit this vulnerability without requiring network connectivity or elevated privileges beyond standard user accounts. The repeated binding operations create a cumulative memory leak that eventually leads to system instability and potential system crashes.
The operational impact of this vulnerability extends beyond simple resource exhaustion, as it provides a straightforward method for local users to perform denial of service attacks against affected systems. The memory consumption pattern follows a predictable progression where each binding operation adds to the cumulative memory footprint, making it possible for an attacker to systematically consume all available memory resources. This type of vulnerability particularly affects systems that rely heavily on IrDA functionality or those that might be running services that utilize infrared communication protocols, potentially disrupting critical operations in embedded systems, IoT devices, or specialized industrial equipment that depend on these communication mechanisms. The attack vector is considered low complexity since it only requires local access and the ability to create and bind AF_IRDA sockets, making it accessible to a wide range of potential attackers.
Mitigation strategies for CVE-2018-6554 primarily focus on upgrading affected systems to kernel versions 4.17 or later, where the memory leak has been addressed through proper memory management procedures in the IrDA implementation. System administrators should prioritize patching affected systems, particularly those running older kernel versions that may be exposed to local attackers. Additionally, monitoring system memory usage and implementing automated alerts for unusual memory consumption patterns can help detect exploitation attempts. The vulnerability demonstrates the importance of proper memory management in kernel code, as highlighted by ATT&CK technique T1499.001, which covers resource exhaustion attacks. Organizations should also consider implementing access controls to limit local user privileges where possible, though this does not address the core vulnerability. The fix implemented in kernel 4.17 demonstrates proper memory management practices that ensure allocated resources are correctly released during socket binding operations, preventing the accumulation of memory leaks that could lead to system instability.