If a size parameter is stored in variables of type size_t, but operated on in such a way that it is temporarily stored in a variable that is not of type size_t, then the original value of the size may be truncated. When this value is passed to malloc, calloc, or realloc, a block of memory with an unexpected size may be allocated.
To prevent this error, size parameters should not be operated on in a way that they are stored in different data types. Furthermore, it is recommended that size parameters are checked for integer conversion errors before they are supplied to malloc, calloc, or realloc.