add check for wrapping of address + size in exec()
add check for wrapping of address + size in exec()

voytovichs/xv6-public,CHRISTOPHERDIEHL/xv6,CHRISTOPHERDIEHL/xv6,gw/xv6,phf/xv6-public,lord021/Assignment2,lord021/Assignment2,gw/xv6,nwf/xv6-public,shyandsy/xv6,shyandsy/xv6,ManaPoustizadeh/OS-finalProject,lord021/Assignment2,nwf/xv6-public,nwf/xv6-public,ManaPoustizadeh/OS-finalProject,voytovichs/xv6-public,gw/xv6,ManaPoustizadeh/OS-finalProject,nwf/xv6-public,CHRISTOPHERDIEHL/xv6,gw/xv6,CHRISTOPHERDIEHL/xv6,shyandsy/xv6,shyandsy/xv6,phf/xv6-public,lord021/Assignment2,gw/xv6,voytovichs/xv6-public,ManaPoustizadeh/OS-finalProject,voytovichs/xv6-public,phf/xv6-public,nwf/xv6-public,phf/xv6-public,voytovichs/xv6-public,shyandsy/xv6