How to check what a pointer writes in allocated memory?

Question

I come across this question during a discussion with an interviewer:

If I allocated 4 bytes of memory from malloc.

int *p = (int*) malloc(4);

Now, if I moved the pointer to 4 bytes.

p++;

And now the pointer points to a memory that contains 4 bytes of memory allocated by malloc. Suppose this memory has read / write permission.

*p=4; 

This means that the pointer exits the allocated memory.

Now consider the case where I allocated some memory, but whenever my pointer leaves the allocated and writes to this memory, I want to be informed, but how

I only have malloc and am free to use.

Answer 1

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Answer 2

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