CVE-2026-80770 in Linux
Summary
by MITRE • 09/04/2026
In the Linux kernel, the following vulnerability has been resolved:
HID: nintendo: stop device IO before hid_hw_stop on probe failure
nintendo_hid_probe() calls hid_device_io_start() before joycon_init() and joycon_leds_create(). If either fails, the error path jumps to err_close which calls hid_hw_close()/hid_hw_stop() without first calling hid_device_io_stop().
hid_hw_stop() does not stop device IO, so hid_input_report() may still run and access driver data that is being torn down, resulting in a use-after-free.
Add an err_io_stop label that calls hid_device_io_stop() before hid_hw_close(), and point the two post-io_start error paths at it.
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Analysis
by VulDB Data Team • 09/04/2026
The identified vulnerability resides within the Nintendo HID driver subsystem of the Linux kernel, specifically affecting the initialization sequence during device probing. The core issue stems from an improper handling of resource cleanup when hardware initialization fails partway through the probe process. During normal operation, the nintendo_hid_probe function initiates input device operations by calling hid_device_io_start before proceeding with complex setup routines such as joycon_init and joycon_leds_create. This sequence is designed to ensure that the driver can immediately begin processing incoming reports from the connected hardware once it becomes available. However, this design introduces a critical race condition if any of these subsequent initialization steps fail, triggering an error path that attempts to tear down the device interface without properly halting active input operations first.
The technical flaw lies in the order and completeness of the cleanup routine invoked upon probe failure. When joycon_init or joycon_leds_create returns an error code, control flow jumps to a label named err_close which executes hid_hw_close followed by hid_hw_stop. The fundamental problem is that hid_hw_stop does not inherently stop device input operations; it primarily handles hardware-level disconnection and resource deallocation at the HID core level. Consequently, if hid_device_io_start was previously called but never matched with a corresponding hid_device_io_stop call before teardown begins, the kernel may continue to process incoming HID reports while the driver's internal data structures are being freed or invalidated. This creates a window where interrupt handlers or workqueues associated with input processing can access memory regions that have already been released by the failing initialization routine.
This race condition results in a use-after-free vulnerability, classified under CWE-416 as an error handling issue leading to invalid memory reference. The operational impact is severe, potentially allowing for kernel panic due to null pointer dereferences or general protection faults when accessing freed structures. In more sophisticated attack scenarios, particularly where the attacker has physical access to inject malformed HID reports during the brief window of probe failure and teardown, this could be leveraged for arbitrary code execution with kernel privileges. The vulnerability is exploitable because the timing between the initiation of input processing and the premature termination of hardware resources allows external devices or maliciously crafted inputs to trigger callbacks into uninitialized or freed memory contexts within the driver stack.
From a threat modeling perspective aligned with MITRE ATT&CK, this flaw relates to techniques involving exploitation of race conditions during resource initialization and teardown phases. It falls under the broader category of improper input validation and error handling that leads to security-relevant state inconsistencies. The specific mechanism involves manipulating the lifecycle management of kernel objects where asynchronous events (incoming HID reports) interact with synchronous cleanup routines without proper synchronization barriers or sequential integrity checks. This type of vulnerability is particularly dangerous in embedded systems like Nintendo controllers because they are frequently connected and disconnected, increasing the frequency of probe operations and thus expanding the attack surface for timing-based exploits.
The resolution implemented addresses this by introducing a dedicated error handling label named err_io_stop that ensures hid_device_io_stop is called before any hardware-level cleanup functions such as hid_hw_close or hid_hw_stop. By redirecting both post-io_start failure paths to this new label, the patch guarantees that input processing is explicitly halted and synchronized with the driver's internal state before memory deallocation occurs. This change enforces a strict ordering constraint where all active asynchronous operations must be quiesced prior to releasing associated resources. The fix aligns with best practices for kernel driver development which mandate symmetric start-stop calls for any subsystem-managed I/O streams to prevent dangling references and ensure atomicity in resource lifecycle management.
Mitigation strategies beyond the immediate patch involve ensuring that drivers adhere strictly to initialization order dependencies where hardware-specific setup must complete before enabling input processing unless there is robust locking mechanisms to protect concurrent access during partial failures. Developers should audit similar HID drivers for symmetric start-stop patterns, particularly those involving asynchronous report handling and dynamic memory allocation tied to device presence. Regular static analysis tools configured to detect mismatched resource acquisition and release sequences can help identify such issues early in the development cycle. Additionally, implementing comprehensive logging around probe success and failure paths aids in debugging race conditions that may not manifest immediately but could lead to instability under high-load or rapid connection-disconnection scenarios common in peripheral-heavy environments.