CVE-2023-52781 in Linux
Summary
by MITRE • 05/21/2024
In the Linux kernel, the following vulnerability has been resolved:
usb: config: fix iteration issue in 'usb_get_bos_descriptor()'
The BOS descriptor defines a root descriptor and is the base descriptor for accessing a family of related descriptors.
Function 'usb_get_bos_descriptor()' encounters an iteration issue when skipping the 'USB_DT_DEVICE_CAPABILITY' descriptor type. This results in the same descriptor being read repeatedly.
To address this issue, a 'goto' statement is introduced to ensure that the pointer and the amount read is updated correctly. This ensures that the function iterates to the next descriptor instead of reading the same descriptor repeatedly.
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Analysis
by VulDB Data Team • 09/25/2025
The vulnerability identified as CVE-2023-52781 resides within the Linux kernel's USB subsystem, specifically affecting the usb_get_bos_descriptor() function. This issue represents a critical iteration flaw that fundamentally impacts how the kernel processes USB Binary Object Store (BOS) descriptors. The BOS descriptor serves as a root descriptor that provides access to a family of related USB descriptors, making it essential for proper USB device enumeration and configuration. When a USB device connects to a Linux system, the kernel must correctly parse these descriptors to understand device capabilities and establish appropriate communication protocols. The vulnerability manifests during the parsing of device capability descriptors, which are crucial for identifying advanced USB features such as USB 3.0 super speed capabilities, wireless USB extensions, and other enhanced functionalities that modern USB devices may support.
The technical flaw within usb_get_bos_descriptor() stems from an incorrect iteration mechanism when processing USB_DT_DEVICE_CAPABILITY descriptor types. This specific descriptor type is used to indicate various device capabilities beyond basic USB functionality, including super speed operation, precise time reporting, and other advanced features. The function's implementation fails to properly advance the read pointer when encountering these capability descriptors, causing the kernel to repeatedly read the same descriptor instead of advancing to the next available descriptor in the BOS structure. This iteration issue creates a condition where the kernel's USB subsystem enters an infinite loop or repeated processing of identical data, consuming excessive CPU resources and potentially causing system instability. The problem directly violates the expected behavior of descriptor parsing routines, which should maintain proper state tracking and pointer advancement through the descriptor chain to ensure comprehensive and efficient processing of all available USB device information.
The operational impact of this vulnerability extends beyond simple performance degradation to potentially compromise system stability and security. When the kernel repeatedly processes the same USB descriptor, it can lead to resource exhaustion, causing denial of service conditions where legitimate USB device operations are blocked or delayed. The repeated processing also introduces timing vulnerabilities that could be exploited by malicious actors to craft specific USB devices that trigger resource exhaustion or system hangs. Additionally, this flaw affects the kernel's ability to properly enumerate USB devices, potentially preventing devices from being recognized or functioning correctly. The vulnerability affects all Linux systems running kernel versions that include the affected usb_get_bos_descriptor() function, making it a widespread concern across various device types and system configurations. This issue particularly impacts systems with USB 3.0 and newer devices that rely heavily on BOS descriptors for proper operation, potentially causing cascading failures in USB subsystem functionality and device compatibility.
The fix for CVE-2023-52781 addresses the core iteration problem by implementing a goto statement that ensures proper pointer advancement and data read tracking within the usb_get_bos_descriptor() function. This solution directly addresses the root cause by guaranteeing that when the function encounters a USB_DT_DEVICE_CAPABILITY descriptor, it correctly updates both the read pointer and the amount of data processed before continuing to the next descriptor in the sequence. This remediation aligns with standard software engineering practices for descriptor parsing and iteration control, ensuring that state variables are properly maintained throughout the parsing process. The fix demonstrates proper adherence to CWE-129 principles regarding input validation and iteration bounds checking, preventing the condition where a loop processes the same data repeatedly. From an ATT&CK perspective, this vulnerability and its remediation relate to privilege escalation and denial of service tactics, as the issue could be leveraged to disrupt system operations or potentially gain elevated privileges through malformed USB device interactions. The implementation of the goto statement represents a targeted fix that maintains backward compatibility while resolving the specific iteration flaw that could be exploited in various attack scenarios involving USB device enumeration and processing.