Re: [PATCH 0/2] MR5984: win32u: Use the desktop shared memory for is_virtual_desktop.

[Grigory Vasilyev (＠h0tc0d3)]

Grigory Vasilyev (@h0tc0d3) commented about dlls/win32u/winstation.c:
> BOOL is_virtual_desktop(void)
>  {
> -    HANDLE desktop = NtUserGetThreadDesktop( GetCurrentThreadId() );
> -    USEROBJECTFLAGS flags = {0};
> -    DWORD len;
> +    struct object_lock lock = OBJECT_LOCK_INIT;
> +    const desktop_shm_t *desktop_shm;
> +    BOOL ret = FALSE;
> +    UINT status;
>
> -    if (!NtUserGetObjectInformation( desktop, UOI_FLAGS, &flags, sizeof(flags), &len )) return FALSE;
> -    return !!(flags.dwFlags & DF_WINE_VIRTUAL_DESKTOP);
> +    while ((status = get_shared_desktop( &lock, &desktop_shm )) == STATUS_PENDING)
> +        ret = !!(desktop_shm->flags & DF_WINE_VIRTUAL_DESKTOP);

Can we get an incorrect pointer in desktop_shm, for example NULL, which will lead to null pointer dereference?
It's probably better to move to ELSE after checking the status.
```C
if (status) ret = FALSE;
else ret = !!(desktop_shm->flags & DF_WINE_VIRTUAL_DESKTOP);
```

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https://gitlab.winehq.org/wine/wine/-/merge_requests/5984#note_75018