Hi,

a long time ago someone mentioned that sethostname() and setdomainname() 
properly return -EFAULT when passing an invalid pointer to the new name, but 
instead of leaving the fields in system_utsname unchanged the nodename and 
domainname are set to an empty string.

The behaviour of sys_sethostname() can be verified using the attached program 
(sethostname.c); sys_setdomainname() is almost the same so I guess that it 
has the same defect :-)

The attached patches fix this. 

Stephan