old_password() functions   
The PASSWORD() and OLD_PASSWORD() functions could lead to   
memory reads outside of an internal buffer when used with BLOB   
arguments.   
  
String::c_ptr() assumes there is at least one extra byte  
in the internally allocated buffer when adding the trailing  
'\0'.  This, however, may not be the case when a String object  
was initialized with externally allocated buffer.  
  
The bug was fixed by adding an additional "length" argument to  
make_scrambled_password_323() and make_scrambled_password() in  
order to avoid String::c_ptr() calls for  
PASSWORD()/OLD_PASSWORD().  
  
However, since the make_scrambled_password[_323] functions are  
a part of the client library ABI, the functions with the new  
interfaces were implemented with the 'my_' prefix in their  
names, with the old functions changed to be wrappers around  
the new ones to maintain interface compatibility.