CVE-2023-54159 in Linux
Summary
by MITRE • 12/24/2025
In the Linux kernel, the following vulnerability has been resolved:
usb: mtu3: fix kernel panic at qmu transfer done irq handler
When handle qmu transfer irq, it will unlock @mtu->lock before give back request, if another thread handle disconnect event at the same time, and try to disable ep, it may lock @mtu->lock and free qmu ring, then qmu irq hanlder may get a NULL gpd, avoid the KE by checking gpd's value before handling it.
e.g. qmu done irq on cpu0 thread running on cpu1
qmu_done_tx() handle gpd [0]
mtu3_requ_complete() mtu3_gadget_ep_disable() unlock @mtu->lock give back request lock @mtu->lock mtu3_ep_disable() mtu3_gpd_ring_free() unlock @mtu->lock lock @mtu->lock get next gpd [1]
[1]: goto [0] to handle next gpd, and next gpd may be NULL.
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Analysis
by VulDB Data Team • 01/03/2026
The vulnerability CVE-2023-54159 represents a critical race condition in the Linux kernel's USB multi-threaded unit3 (mtu3) driver that can lead to kernel panic and system instability. This issue specifically affects the handling of QMU (Queue Management Unit) transfer completion interrupts within the USB gadget framework, where concurrent operations between interrupt handlers and thread contexts create a dangerous synchronization scenario. The flaw manifests when the QMU transfer done interrupt handler processes requests while another thread simultaneously handles device disconnection events, creating a potential for NULL pointer dereference that can crash the entire kernel.
The technical root cause stems from improper locking sequence and resource management within the mtu3 gadget driver implementation. During QMU transfer completion processing, the interrupt handler unlocks the mtu->lock mutex before completing and returning the USB request, but this timing window allows another thread to execute device disconnection routines. When this occurs, the disconnection handler attempts to disable endpoints, which requires acquiring the same mtu->lock mutex and subsequently frees the QMU ring structure. However, the original interrupt handler may still be processing and attempting to access the now-freed QMU ring entries, resulting in a NULL pointer dereference scenario that triggers kernel panic.
This vulnerability directly maps to CWE-362, which describes a race condition in concurrent programming where multiple threads access shared resources without proper synchronization, and it aligns with ATT&CK technique T1059.003 for kernel-level privilege escalation through system instability. The flaw demonstrates poor resource lifecycle management where the interrupt handler assumes QMU ring entries remain valid throughout its execution, failing to account for the possibility that concurrent operations might have freed these resources. The race condition occurs specifically during the transition from one QMU ring entry to the next, where the second entry may have been freed by the disconnection handler, creating a NULL pointer access that terminates kernel execution.
The operational impact of CVE-2023-54159 extends beyond simple system crashes to potentially compromise system availability and stability in embedded USB gadget implementations. Systems utilizing USB device controllers that employ the mtu3 driver, particularly those in automotive, industrial, or networking equipment where USB gadget functionality is critical, face significant risk of unexpected system failures. The vulnerability can be triggered during normal USB data transfer operations when disconnection events occur concurrently with transfer completion interrupts, making it particularly dangerous in environments where USB devices are frequently connected and disconnected. Attackers could potentially exploit this timing window to cause persistent system instability, though direct remote exploitation is limited due to the requirement for concurrent execution paths and specific hardware configurations.
Mitigation strategies for CVE-2023-54159 require implementing proper synchronization mechanisms to prevent concurrent access to QMU ring structures during interrupt handling. The fix should ensure that QMU ring entries are validated before access, implementing a check for NULL pointers before processing each gpd (generic packet descriptor) entry in the interrupt handler. Additionally, the driver should maintain proper reference counting or use memory barriers to prevent premature freeing of QMU ring structures during active interrupt processing. System administrators should apply the kernel patch that addresses this specific race condition, ensuring that the mtu3 driver properly handles concurrent access patterns between interrupt contexts and thread contexts. Organizations should also implement monitoring for unusual USB device disconnection patterns that might indicate exploitation attempts, while maintaining current kernel versions that contain the appropriate fixes. The solution must maintain backward compatibility while ensuring that the synchronization primitives correctly prevent the race condition without introducing performance degradation or additional complexity to the USB gadget framework.