CVE-2016-5400 in Linux
Summary
by MITRE
Memory leak in the airspy_probe function in drivers/media/usb/airspy/airspy.c in the airspy USB driver in the Linux kernel before 4.7 allows local users to cause a denial of service (memory consumption) via a crafted USB device that emulates many VFL_TYPE_SDR or VFL_TYPE_SUBDEV devices and performs many connect and disconnect operations.
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Analysis
by VulDB Data Team • 09/09/2022
The vulnerability identified as CVE-2016-5400 represents a critical memory management flaw within the Linux kernel's airspy USB driver implementation. This issue resides in the airspy_probe function located at drivers/media/usb/airspy/airspy.c and affects kernel versions prior to 4.7. The flaw manifests as a memory leak that occurs during the device probing process when handling USB devices that emulate multiple VFL_TYPE_SDR or VFL_TYPE_SUBDEV devices. The vulnerability exploits the driver's insufficient memory management during connect and disconnect operations, creating a persistent memory consumption issue that can lead to system instability.
The technical execution of this vulnerability involves a local attacker who can craft a malicious USB device designed to emulate numerous Software Defined Radio (SDR) and subdevice virtual device types. When such a device is connected to a vulnerable system, the airspy driver repeatedly processes connection and disconnection events without properly releasing allocated memory resources. Each iteration of the connect-disconnect cycle consumes additional memory while failing to reclaim previously allocated memory blocks, resulting in progressive memory exhaustion. This memory leak pattern directly violates the principles of proper resource management and can be categorized under CWE-401 as "Improper Release of Memory Before Removing Last Reference" and aligns with ATT&CK technique T1499.200 for resource consumption attacks.
The operational impact of this vulnerability extends beyond simple memory consumption to encompass potential system-wide denial of service conditions. As memory becomes increasingly consumed, the system may experience degraded performance, application crashes, or complete system instability. The vulnerability is particularly concerning because it requires only local physical access to a system to exploit, making it accessible to attackers with physical proximity to target systems. This characteristic places it within the ATT&CK framework's T1059 category of execution techniques, as it can be leveraged to disrupt system operations without requiring network connectivity or complex remote exploitation methods. The memory leak can accumulate to the point where the system becomes unresponsive, effectively rendering the device unusable for legitimate SDR operations and potentially affecting other system functions that depend on available memory resources.
Mitigation strategies for CVE-2016-5400 primarily involve upgrading to Linux kernel version 4.7 or later, where the memory leak has been addressed through proper resource management implementation. System administrators should also implement monitoring solutions to detect unusual memory consumption patterns that may indicate exploitation attempts. Additionally, physical security measures should be enhanced to prevent unauthorized access to USB ports, as this vulnerability requires local physical access for exploitation. The fix implemented in kernel 4.7 includes proper memory deallocation mechanisms within the airspy_probe function, ensuring that all allocated resources are released appropriately during device connection and disconnection events, thereby preventing the accumulation of unreleased memory blocks that characterized the original vulnerability.