memcpy can not be used in driver

[rjw999]

memcpy in read and write should be replaced by copy_from_user or copy_to_user
because the buf point to the userspace address which can not be direct accessed in kernel

[durellinux]

Thanks for pointing it out.
I am going to work on the drivers soon, since they do not manage well multiple writes scenario, so I will include your suggestion too.