[PATCH xserver] xwayland: Don't crash on WarpPointer(dest_w = None)

[Peter Hutterer]

On Thu, Apr 12, 2018 at 05:24:08PM -0400, Adam Jackson wrote:
> Turns out that's legal, and xts exercises it, and we crash:
> 
>     Thread 1 "Xwayland" received signal SIGSEGV, Segmentation fault.
>     dixGetPrivate (key=0x813660 <xwl_window_private_key>, privates=0x20) at ../../include/privates.h:122
>     122	    return (char *) (*privates) + key->offset;
>     (gdb) bt
>     #0  dixGetPrivate (key=0x813660 <xwl_window_private_key>, privates=0x20) at ../../include/privates.h:122
>     #1  dixLookupPrivate (key=0x813660 <xwl_window_private_key>, privates=0x20) at ../../include/privates.h:166
>     #2  xwl_window_of_top (window=0x0) at xwayland.c:128
>     #3  xwl_cursor_warped_to (device=<optimized out>, screen=0x268b6e0, client=<optimized out>, window=0x0, sprite=0x300bb30,
>         x=2400, y=1350) at xwayland.c:292
>     #4  0x00000000005622ec in ProcWarpPointer (client=0x32755d0) at events.c:3618
> 
> In this case, x/y are the screen-space coordinates where the pointer
> ends up, and we need to look up the (X) window there.
> 
> Signed-off-by: Adam Jackson <ajax at redhat.com>

Reviewed-by: Peter Hutterer <peter.hutterer at who-t.net>

Cheers,
   Peter

> ---
>  hw/xwayland/xwayland.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/hw/xwayland/xwayland.c b/hw/xwayland/xwayland.c
> index e65d8b7e77..dd074c3415 100644
> --- a/hw/xwayland/xwayland.c
> +++ b/hw/xwayland/xwayland.c
> @@ -289,6 +289,9 @@ xwl_cursor_warped_to(DeviceIntPtr device,
>      if (!xwl_seat)
>          xwl_seat = xwl_screen_get_default_seat(xwl_screen);
>  
> +    if (!window)
> +        window = XYToWindow(sprite, x, y);
> +
>      xwl_window = xwl_window_of_top(window);
>      if (!xwl_window && xwl_seat->focus_window) {
>          focus = xwl_seat->focus_window->window;
> -- 
> 2.17.0