CVE-2026-99069 in Linux
Summary
by MITRE • 10/23/2026
In the Linux kernel, the following vulnerability has been resolved:
Input: ati_remote2 - fix type confusion in device attribute handlers
Previously, the channel_mask and mode_mask attributes were registered on the parent usb_device via sysfs_create_group(). When commit b20d6bf8014b ("Input: ati-remote2 - use driver core to instantiate device attributes") converted the driver to let the driver core manage them via dev_groups in struct usb_driver, the attributes moved to the bound usb_interface devices, but the show and store callbacks were not updated accordingly.
As a result, the callbacks still invoked to_usb_device() on a device pointer belonging to a struct usb_interface, producing an invalid usb_device pointer.
Use to_usb_interface() directly in the attribute handlers to obtain the interface and its driver data.
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Analysis
by VulDB Data Team • 10/23/2026
The vulnerability identified as ati_remote2 type confusion represents a classic instance of improper type casting within the Linux kernel input subsystem, specifically affecting the ATI Remote 2 USB device driver. This flaw originated from an architectural refactoring where the method for managing sysfs attributes was updated to align with modern driver core practices. Previously, channel_mask and mode_mask attributes were registered directly on the parent usb_device structure using sysfs_create_group. However, a subsequent commit shifted this responsibility to the driver core by utilizing dev_groups within the struct usb_driver definition. This change caused these device attributes to be instantiated on bound usb_interface devices rather than the original usb_device objects. The critical error lies in the fact that while the registration location changed, the corresponding show and store callback functions were not updated to reflect this structural shift.
From a technical perspective, the core of the vulnerability is a type confusion resulting from an incorrect pointer cast. When sysfs invokes these attribute handlers for the channel_mask or mode_mask attributes on a usb_interface device, the callbacks still attempt to retrieve context by calling to_usb_device() on the passed device pointer. Since the pointer actually refers to a struct usb_interface rather than a struct usb_device, this macro performs an invalid offset calculation based on incorrect assumptions about memory layout and structure relationships. Consequently, the function returns a garbage or null pointer that does not correspond to valid kernel memory associated with the actual USB device. This misinterpretation of data types leads to dereferencing an invalid address, which can trigger a kernel panic due to an oops in interrupt context or general protection fault, effectively causing a denial of service against the system hosting the affected hardware.
The operational impact of this vulnerability is primarily localized to systems utilizing ATI Remote 2 USB devices and attempting to read or write their configuration attributes via sysfs. An attacker with local access who can interact with these specific device nodes could trigger the invalid memory dereference, leading to immediate kernel instability. While remote exploitation is not applicable due to the requirement for physical interaction with the hardware interface and root privileges typically needed to manipulate sysfs entries in this manner, the vulnerability remains significant because it compromises system stability through a simple user-space action on an exposed device attribute. The flaw highlights the risks associated with refactoring driver code without ensuring that all dependent callback functions are correctly adapted to new structural hierarchies within the kernel's USB subsystem.
To mitigate this risk, the resolution involves correcting the type casting logic within the show and store callbacks for these attributes. Instead of attempting to cast the device pointer to a usb_device structure using an inappropriate macro, the handlers must now use to_usb_interface() to correctly obtain the interface object from which driver data can be safely retrieved. This ensures that subsequent operations access valid memory structures associated with the actual hardware instance. Administrators should ensure their kernels are updated to include this patch. Furthermore, developers working on similar USB drivers should adhere strictly to CWE-823 guidelines regarding improper use of validated references and follow ATT&CK technique T1059 related to command scripting or system configuration changes by ensuring that attribute handlers accurately reflect the underlying device hierarchy they interact with, thereby preventing type confusion vulnerabilities in future code revisions.