[Qemu-stable] [PATCH] sdl2: fix crash in handle_windowevent() when restoring the screen size

[Alberto Garcia]

The Ctrl-Alt-u keyboard shortcut restores the screen to its original
size. In the SDL2 UI this is done by destroying the window and
creating a new one. The old window emits SDL_WINDOWEVENT_HIDDEN when
it's destroyed, but trying to call SDL_GetWindowFromID() from that
event's window ID returns a null pointer. handle_windowevent() assumes
that the pointer is never null so it results in a crash.

Signed-off-by: Alberto Garcia <address@hidden>
Cc: Gerd Hoffmann <address@hidden>
---
 ui/sdl2.c | 4 ++++
 1 file changed, 4 insertions(+)

I sent this to qemu-devel a week ago, but this also affects the stable
release, hence I'm sending it here too.

http://patchwork.ozlabs.org/patch/480186/

diff --git a/ui/sdl2.c b/ui/sdl2.c
index 60e3c3b..f10c6a4 100644
--- a/ui/sdl2.c
+++ b/ui/sdl2.c
@@ -511,6 +511,10 @@ static void handle_windowevent(SDL_Event *ev)
 {
     struct sdl2_console *scon = get_scon_from_window(ev->window.windowID);
 
+    if (!scon) {
+        return;
+    }
+
     switch (ev->window.event) {
     case SDL_WINDOWEVENT_RESIZED:
         {
-- 
2.1.4