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

RDMA/core: Validate the passed in fops for ib_get_ucaps()

Sashiko pointed out it is not safe to rely only on the devt because
char/block alias so if the user finds a block device with the same dev_t
it can masquerade as a ucap cdev fd.

Test the f_ops to only accept authentic cdevs.