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

ALSA: ac97: fix a double free in snd_ac97_controller_register()

If ac97_add_adapter() fails, put_device() is the correct way to drop
the device reference. kfree() is not required.
Add kfree() if idr_alloc() fails and in ac97_adapter_release() to do
the cleanup.

Found by code review.