So instead of something like this:
```
int smm_handler_xyx(size_t base, size_t size)
{
    if (function_using_region(base, size)) {
        return -1;
    }
}
int function_using_region(size_t base, size_t size)
{
    struct region r;
    if (region_create_untrusted(&r, base, size)) {
        return -1;
    }
    ...
}
```
I like it more like this:
```
int smm_handler_xyx(size_t base, size_t size)
{
    if (base + size < base) {
        return -1; // overflow detected (possible malicious input values)
    }
    function_using_region(base, size);
}
void function_using_region(size_t base, size_t size)
{
    struct region r = region_create(base, size);
    ...
}
```