CVE-2026-68205: media: v4l2-fwnode: Fix subdev owner overwritten in v4l2_async_register_subdev_sensor()

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

media: v4l2-fwnode: Fix subdev owner overwritten in v4l2asyncregistersubdevsensor()

The v4l2 helper v4l2asyncregistersubdevsensor() calls v4l2asyncregistersubdev(), which is a macro that expands to v4l2asyncregistersubdev(sd,THISMODULE). Since the macro is expanded inside v4l2-fwnode.c, THISMODULE resolves to the v4l2-fwnode module rather than the sensor driver module that originally set sd->owner. When v4l2-fwnode is built-in, THISMODULE evaluates to NULL, which then overwrites the sensor driver's owner with NULL.

This causes the problem that the sensor module's reference count is never incremented during async registration, so the module can be removed while the subdevice is still in use by a notifier (e.g., a CSI-2 receiver bridge driver).

Fix this by renaming v4l2asyncregistersubdevsensor() to v4l2asyncregistersubdevsensor() with an added explicit module argument and introducing a wrapper macro: #define v4l2asyncregistersubdevsensor(sd) \ v4l2asyncregistersubdevsensor(sd, THISMODULE)

This ensures the sensor driver module is properly referenced even when the sensor driver does not init the owner field before calling v4l2asyncregistersubdevsensor() and prevents premature module removal.