Consequences of this buffer overflow?

Question

So here I believe I have a small buffer overflow problem I found when reviewing someone else\'s code. It immediately struck me as incorrect, and potentially dangerous, but a

Answer 1

Many historic malloc implementations put bookkeeping data immediately before and/or after the allocated block. It's possible that you're overwriting such data, in which case you would not see any error/crash until you try to free the memory (or perhaps free whatever the next block happens to be). Likewise, it's possible that the bookkeeping information for a subsequent allocation will later overwrite your string.

I suspect modern malloc implementations make some effort to protect against heap corruption by padding allocations with integrity-check data, so if you're lucky, nothing bad will happen or you might get a warning message during a later allocation/free operation.