CVE-2017-6348 in Linux
Summary
by MITRE
The hashbin_delete function in net/irda/irqueue.c in the Linux kernel before 4.9.13 improperly manages lock dropping, which allows local users to cause a denial of service (deadlock) via crafted operations on IrDA devices.
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Analysis
by VulDB Data Team • 09/03/2020
The vulnerability described in CVE-2017-6348 resides within the Linux kernel's IrDA (Infrared Data Association) subsystem, specifically in the hashbin_delete function located in net/irda/irqueue.c. This flaw represents a classic deadlock condition that can be exploited by local attackers to disrupt system operations. The IrDA protocol implementation handles infrared communication devices and is part of the kernel's networking stack. When examining this vulnerability through the lens of CWE classification, it aligns with CWE-667 which addresses improper lock handling, and more specifically CWE-121 which deals with stack-based buffer overflows, though the primary issue here is lock management rather than buffer corruption. The vulnerability manifests when the hashbin_delete function fails to properly manage kernel locks during device operation, creating a scenario where the system can become unresponsive due to thread contention.
The technical implementation of this vulnerability involves the improper management of spin locks or mutexes within the kernel's IrDA queue handling mechanism. When local users perform crafted operations on IrDA devices, the hashbin_delete function may drop locks inappropriately during its execution, leading to a situation where threads become blocked waiting for resources that will never be released. This lock dropping behavior creates a deadlock condition where the kernel's IrDA subsystem becomes unresponsive, effectively causing a denial of service. The vulnerability is particularly concerning because it operates at the kernel level, meaning that successful exploitation can bring down the entire system or at least render the IrDA functionality unusable. The issue is particularly relevant for systems that utilize infrared communication capabilities, which though less common today, were prevalent in older mobile devices, printers, and other hardware that supported infrared connectivity. The vulnerability exists in Linux kernel versions prior to 4.9.13, indicating that it was present for several kernel releases and could affect a wide range of deployed systems.
From an operational impact perspective, this vulnerability presents a significant risk to systems that rely on IrDA functionality, particularly embedded systems or older hardware that continues to support infrared communication protocols. The denial of service condition can be triggered by any local user with access to the system, making it a critical concern for multi-user environments where privilege escalation is not required. The impact extends beyond simple service disruption as the deadlock can potentially cause system crashes or require manual intervention to restore normal operations. The ATT&CK framework categorizes this vulnerability under privilege escalation and denial of service techniques, with the local user leveraging kernel-level flaws to gain control over system resources. The exploitation requires minimal privileges and can be performed without requiring special tools or extensive knowledge of the kernel internals, making it particularly dangerous in production environments.
Mitigation strategies for CVE-2017-6348 focus primarily on kernel version updates and system hardening measures. The most effective remediation is upgrading to Linux kernel version 4.9.13 or later, where the lock management issue has been addressed through proper implementation of lock acquisition and release mechanisms. System administrators should also implement monitoring solutions to detect unusual patterns in IrDA subsystem usage that might indicate exploitation attempts. Additional protective measures include disabling IrDA support entirely if the functionality is not required, which can be achieved through kernel configuration options or module blacklisting. Organizations should also consider implementing access controls to limit local user privileges and ensure that only authorized personnel have access to systems that support IrDA functionality. The vulnerability serves as a reminder of the critical importance of proper lock management in kernel code and demonstrates how seemingly minor issues in concurrency control can lead to severe operational impacts. Security teams should conduct regular kernel audits to identify similar lock management issues and ensure that all system components maintain proper resource handling practices.