As our moderator pointed out, sounds like NX. Use mmap() with   
   PROT_READ|PROT_WRITE|PROT_EXEC or just PROT_WRITE and then mprotect()   
   your region to PROT_READ|PROT_EXEC.   
      
   If you're on an i386, then it's probably some kernel hardening patch   
   that makes the heap non executable.   
   ./ck   
   --   
   Chariton Karamitas   
   Electrical and Computer Engineering Department   
   Fuculty of Engineering   
   Aristotle University of Thessaloniki, Greece   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)