Fill allocated memory with 0xAA and scribble deallocated memory with 0x5.
Scribble will make it rather obvious that you're using a memory block after it's free'd by overwriting any data that used to be in the memory block upon free.
Definition of Scribble : To write hastily or carelessly without regard to legibility or form. To cover with careless or worthless writings or drawings.
Scribble will make it rather obvious that you're using a memory block after it's free'd by overwriting any data that used to be in the memory block upon free.