⚪ ALSA: usb-audio: avoid kobject path lookup in DualSense match (Linux Linux)

Description

In the Linux kernel, the following vulnerability has been resolved: ALSA: usb-audio: avoid kobject path lookup in DualSense match The DualSense jack-detection input handler verifies that a matching input device belongs to the same physical controller by building kobject path strings for both the input device and the USB audio device, then comparing the path prefix. This was observed when a weak physical connection caused the controller to rapidly disconnect and reconnect. During that repeated hotplug, snd_dualsense_ih_match() can run while the controller's USB device is being disconnected. kobject_get_path() walks ancestor kobjects and dereferences their names; if the USB device kobject name is no longer valid, this can fault in strlen(): RIP: 0010:strlen+0x10/0x30 Call Trace: kobject_get_path+0x34/0x150 snd_dualsense_ih_match+0x49/0xd0 [snd_usb_audio] input_register_device+0x566/0x6a0 ps_probe+0xb89/0x1590 [hid_playstation] The same ownership check can be done without building kobject path strings. The input device is parented below the HID device, USB interface and USB device, so walking the input device parent chain and comparing against the mixer USB device preserves the check without dereferencing kobject names during disconnect.