AZL-100731

In the Linux kernel, the following vulnerability has been resolved:

HID: universal-pidff: stop the device when force-feedback init fails

universal_pidff_probe() starts the device with hid_hw_start() and then, if force-feedback initialisation fails, returns the error through a label that only does "return error". The device is left started.

The HID core does not unwind on the driver's behalf. __hid_device_probe() releases the devres group, closes the report and clears hdev->driver:

if (ret) {
	devres_release_group(&hdev->dev, hdev->devres_group_id);
	hid_close_report(hdev);
	hdev->driver = NULL;
}

The hidraw character device that hid_hw_start() registered through hid_connect() is allocated with kzalloc() and added with cdev_device_add(), so it is not devres-managed and survives that. With hdev->driver NULL, hid_device_remove() skips hid_hw_stop() as well, because it only unwinds while a driver is still attached. The registration therefore outlives the device on both paths.

Opening the surviving /dev/hidrawX writes into freed memory. KASAN reports a use-after-free write from hidraw_open() -> hid_hw_open() -> the transport's open callback, which takes a spinlock inside the freed object. A descriptor that carries a PID usage page and no input reports is enough: hidraw claims the device so hid_hw_start() succeeds, while hid->inputs stays empty so force-feedback init fails. The other failure returns in hid_pidff_init_with_quirks() - no output reports, an allocation failure, pidff_init_fields(), pidff_check_autocenter(), an unusable effect count, input_ff_create() - all reach the same label.

Stop the device on that path. hid-dr.c and hid-emsff.c, which start the device with the same HID_CONNECT_DEFAULT & ~HID_CONNECT_FF mask, already do this. The two earlier gotos must keep returning without hid_hw_stop(), since neither has a started device, so give the path that fails after the start its own label.

Discovered by XBOW, triaged by Baul Lee baul.lee@xbow.com