CVE-2026-93124 in Linux
Summary
by MITRE • 09/18/2026
In the Linux kernel, the following vulnerability has been resolved:
platform/x86: asus-wireless: Fail probe when there is no ACPI match
Every platform driver can be forced to match a device that does not match its list of device IDs because of device_match_driver_override(), so platform drivers that rely on the existence of a device ACPI companion object need to verify its presence.
asus_wireless_probe() returns success when acpi_match_acpi_device() finds no match, leaving behind an input device that never reports anything because the notify handler is not installed. Worse, when the driver is force-bound to a device without an ACPI companion, probe still succeeds and stores a NULL companion pointer, which asus_wireless_remove() later passes to acpi_dev_remove_notify_handler(), leading to a NULL pointer dereference on unbind.
Return -ENODEV when the device does not match the ID table. This also covers the missing-companion case, because acpi_match_acpi_device() rejects a NULL device. Perform the check before allocating any driver state, instead of after the input device has already been registered.
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Analysis
by VulDB Data Team • 09/18/2026
The vulnerability identified in the Linux kernel's asus-wireless platform driver stems from an insufficient validation mechanism during the device probe phase, specifically regarding ACPI companion objects. Platform drivers are susceptible to being force-bound to devices that do not match their designated list of supported hardware identifiers due to the functionality provided by device_match_driver_override(). This override capability allows external mechanisms or configurations to bind a driver to any platform device regardless of whether the hardware is actually compatible with the driver's intended scope. In the context of asus-wireless, which manages wireless switching features on ASUS laptops and devices via ACPI interfaces, the driver relies heavily on the presence of an ACPI companion object to interact with the firmware interface that controls these hardware states.
The core technical flaw lies in how asus_wireless_probe() handles cases where acpi_match_acpi_device() fails to find a matching entry or encounters a NULL device pointer. Previously, when no match was found, the function would erroneously return success rather than an error code. This premature success signal causes the kernel's driver model to proceed with registering the input device node within the system. However, because there is no valid ACPI companion object corresponding to the hardware, the necessary notify handler for receiving wireless state changes from the firmware cannot be installed. Consequently, the registered input device remains non-functional and never reports any events to user space applications that might rely on it for toggling Wi-Fi or Bluetooth states.
The severity of this issue escalates significantly during the driver unbind phase when a NULL pointer dereference occurs. If an administrator or automated tool forces the asus-wireless driver onto a device lacking an ACPI companion, the probe function succeeds and stores a NULL value in the structure representing the ACPI handle. Later, when the driver is removed from that device, either through manual unbinding or system shutdown procedures, the cleanup routine asus_wireless_remove() attempts to invoke acpi_dev_remove_notify_handler(). This function expects a valid pointer to an ACPI device object but receives NULL instead. The attempt to dereference this null address triggers a kernel panic or crash, leading to immediate system instability and potential denial of service for all running processes on the affected machine.
This vulnerability is classified under CWE-476, which denotes a NULL Pointer Dereference, as it involves accessing memory through an invalid pointer that leads to undefined behavior and system crashes. From a tactical perspective within the MITRE ATT&CK framework, this flaw aligns with T1059 Command and Scripting Interpreter or potentially T1211 Exploitation for Defense Evasion if leveraged in conjunction with other vulnerabilities to crash security monitoring agents, though its primary impact is stability-related denial of service. The root cause can also be associated with CWE-787 Out-of-bounds Write or improper resource management principles where resources are allocated without verifying the prerequisites required for their safe usage and subsequent release.
To mitigate this vulnerability, the fix implements a strict validation check at the very beginning of the probe sequence before any driver state is allocated or input devices are registered. The updated logic ensures that if acpi_match_acpi_device() returns no match or encounters a NULL device pointer, the function immediately returns -ENODEV. This error code signals to the kernel's platform bus subsystem that the current hardware does not support this driver, preventing the binding process entirely. By rejecting incompatible devices early in the initialization flow, the system avoids creating orphaned input nodes and eliminates the possibility of passing null pointers to cleanup routines during unbind operations.
System administrators should ensure their Linux kernels are updated with patches addressing this specific asus-wireless probe logic error. For environments where custom driver bindings or overrides are utilized for testing purposes, it is critical to verify that target devices possess valid ACPI descriptors before attempting such bindings. Maintaining up-to-date kernel versions ensures that the defensive programming practices implemented in this fix prevent both functional failures of wireless controls and catastrophic system crashes resulting from improper resource handling during device lifecycle management events.