There are buffer overruns bugs around NativeMemory.Alloc usage

[smourier]

NativeMemory.Alloc allocates a byte count so you should pass half the buffer's size to Shell APIs which are expecting unicode-sized buffers.

Typically, this crashes on my PC:

    public static byte[]? GetThumbnail(IShellLinkW* pShellLink, int size = 32)
    {
            ...
            pwszIconLocation = (char*)NativeMemory.Alloc(256);
            hr = pShellLink->GetIconLocation(pwszIconLocation, 256, &nIconIndex);
            ...

It should be

            hr = pShellLink->GetIconLocation(pwszIconLocation, 128, &nIconIndex);

And in fact IMHO, you should pass bigger buffers to avoid truncation, at least 512 but it can be more (not everything is under the MAX_PATH rule, Microsoft is very unclear about this).