Visual Studio - how to find source of heap corruption errors

Question

I wonder if there is a good way to find the source code that causes a heap corruption error, given the memory address of the data that was written \'outside\' the allocated

Answer 1

Make sure all libraries you are linking to are compiled in the same CLR version as the application you are running - all in Release or all in Debug.

When you compile in either Debug and Release you are actually targeting two different versions of the C runtime library. These versions are quite different and they use different strategies for allocating memory and they use different heaps. But the most important thing to know is that they are NOT compatible with one another.

The Release C runtime library allocated memory as expected, whereas the Debug will add extra information, such as guard blocks to track buffer overflow and the location that called the allocation function, and in turn it allocates more memory than the Release.

If your are linking your application to a mix of DLLs which were built in Release and Debug, you will most likely end up trying to delete an object in one CLR which was created in another. This means you will be trying to free more or less memory than what was allocated to the object and this can corrupt the heap.

You should build your application, as well as attach to libraries which are built under the same configuration, either Release or Debug.

This problem can occur especially in modules that are being compiled with different compilers.

There is a way to work around, which I will mention but do not recommend. If for some reason you still need to build in different modes, this work around will allows for all memory to be allocated and freed from the same shared heap. The API GetProcessHeap will allow you to access the shared heap throughout the different modules. By using the HeapAlloc & HeapFree you can allocate and free memory in the shared heap. Note: the HeapAlloc and HeapFree should replace all calls to malloc and free in your application.