Re: [PATCH] ui/sdl2: fix segment fault caused by null pointer dereference

[Peter Maydell]

On Mon, 27 Apr 2020 at 13:19, Changbin Du <address@hidden> wrote:
>
> I found SDL_GetWindowFromID() sometimes return NULL when I start qemu via
> ssh forwarding even the window has been crated already. I am not sure
> whether this is a bug of SDL, but we'd better check it carefully.
>
> Signed-off-by: Changbin Du <address@hidden>
> ---
>  ui/sdl2.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/ui/sdl2.c b/ui/sdl2.c
> index 3c9424eb42..7c9c93b951 100644
> --- a/ui/sdl2.c
> +++ b/ui/sdl2.c
> @@ -332,6 +332,9 @@ static void handle_keydown(SDL_Event *ev)
>      int gui_key_modifier_pressed = get_mod_state();
>      int gui_keysym = 0;
>
> +    if (!scon)
> +        return;
> +
>      if (!scon->ignore_hotkeys && gui_key_modifier_pressed && 
> !ev->key.repeat) {
>          switch (ev->key.keysym.scancode) {
>          case SDL_SCANCODE_2:
> @@ -412,6 +415,9 @@ static void handle_keyup(SDL_Event *ev)
>  {
>      struct sdl2_console *scon = get_scon_from_window(ev->key.windowID);
>
> +    if (!sconf)
> +        return;

It's generally a good idea to make sure your patch at least compiles
before sending it :-)

QEMU coding style demands {} on all if statements.

thanks
-- PMM