Heap corruption: What could the cause be?

Question

I am investigating a crash due to heap corruption. As this issue is non-trivial and involves analyzing the stack and dump results, I have decided to do a code review of file

Answer 1

Its a common mistake to free() or delete allocated memory more than one. It may help to insert something like *var = NULL after such calls, and to check for != NULL when calling free. Although in C++ its legal to call delete with a NULL variable, calling C - free() will fail.

Also a common problem is to confuse delete and delete [].

Variables allocated with new must be released with delete.

Array allocated with new [] must be released with delete[].

Also make sure not to mix C- style memory management (malloc, calloc, free) with C++ style memory management (new/delete). In legacy code often both are mixed, but things allocated with the one can not be freed with the other.

All of these errors will usually not be recognized by a compiler.