In the Linux kernel, the following vulnerability has been resolved:
tty: clear cdev pointer after cdev_add() failure
tty_cdev_add() drops the cdev reference when cdev_add() fails, but
leaves driver->cdevs[index] pointing to freed memory.
tty_unregister_device() later passes that stale pointer to cdev_del(),
causing a use-after-free.
Clear the slot after dropping the reference.
