Summary

• Buffer overflow = unbounded write past a fixed buffer into adjacent memory.
• Stack order low-to-high: buf → saved RBP → saved return address.
• Overwriting the saved return address hijacks control flow at ret.
• ret2win: padding + address-of-existing-function; find padding via cyclic patterns.
• 64-bit needs valid canonical pointers and 16-byte stack alignment (ret gadget).
• Prevent with bounded copies (fgets, snprintf) plus canaries, ASLR, NX.