Re: [PATCH 0/3] MR3839: kernel32: Add structure size checks to CreateActCtx().

[Nikolay Sivov (＠nsivov)]

On Fri Sep 15 11:30:54 2023 +0000, Dmitry Timoshkov wrote:
> > I don't insist on anything, but only pointing at potential improvements.
>
> I don't see how to avoid the checks in both A and W versions. If you have
> an idea how to do that please share it.

I was thinking something like that:

```
if (flags & FLAG_1)
   size = max(size, FIELDOFFSET(..) + ...);
if (flags & FLAG_2)
   size = max(size, ...);

if (cbSize < size)
{
   SetLastError(...);
   return;
}
```

To make it easier to read you can use just FIELDOFFSET() of the next field.

I think it's fine to duplicate that for A and W functions, and avoid changing Rtl* one at all, as long as we don't provide compatible interface for it, nothing is going to call it successfully anyway.