In earlier versions of KBUS, there was a fixed maximum message size. When this 
was removed, a settable value should have replaced it, but did not. Without 
this, there is nothing to stop a user from creating an incredibly large message 
as a denial of service attack (or just carelessness).

Two values should be supplied: an absolute maximum message size, determined at 
compile time, above which the maximum message size cannot be set, and a default 
maximum message size.

An ioctl should also be introduced to change the current maximum, on a 
particular KBUS device.

A lower limit of greater than the size of a message header (80 bytes on a 
32-bit machine) should be enforced (e.g., 100).