[PATCH] ole32: Add parameter check for clipbrd_wndproc

[Huw Davies]

On Fri, Mar 27, 2020 at 01:26:06PM +0800, Zhipeng Zhao wrote:
> When I use wechat-work to do some clip, there raise a exception.
> 
> Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=48826
> Signed-off-by: Zhipeng Zhao <near2see at 163.com>
> ---
>  dlls/ole32/clipboard.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/dlls/ole32/clipboard.c b/dlls/ole32/clipboard.c
> index 9df37750a3..69a8fc61b2 100644
> --- a/dlls/ole32/clipboard.c
> +++ b/dlls/ole32/clipboard.c
> @@ -2066,6 +2066,11 @@ static LRESULT CALLBACK clipbrd_wndproc(HWND hwnd, UINT message, WPARAM wparam,
>          ole_priv_data_entry *entry;
>  
>          TRACE("(): WM_RENDERFORMAT(cfFormat=%x)\n", cf);
> +        if (!clipbrd || !clipbrd->cached_enum)
> +        {
> +            entry = NULL;
> +            break;
> +        } 
>          entry = find_format_in_list(clipbrd->cached_enum->entries, clipbrd->cached_enum->count, cf);
>  
>          if(entry)

Could you debug this a bit further?  Is clipbrd or
clipbrd->cached_enum NULL?  How does it get to this
state?

Thanks,
Huw.