Model for module_param()
module_param(name, type, perm).
Note that if a parameter is changed by sysfs, the value of that parameter as seen by your module changes, but your module is not notified in any other way. You should probably not make module parameters writable, unless you are prepared to detect the change and react accordingly. (http://www.makelinux.net/ldd3/chp-2-sect-8)
This behaviour could lead to different errors.
nr_uarts is verified on module_init()->serial8250_isa_init_ports() to be less or equal UART_NR.
But user with root permission cat set nr_uarts to any uint value.
Then serial8250_remove() lead to buffer overread on serial8250_ports[i].
Require model for module_param(), which will set variable 'name' (if permission allows write) to __VERIFIER_nondet at least before every handlers' call