From 843293bed0601dd115a70b2f9e94800d6eb2babc Mon Sep 17 00:00:00 2001
From: Sam Lantinga <slouken@libsdl.org>
Date: Wed, 9 Aug 2017 20:26:16 -0700
Subject: [PATCH] Fixed bug 3701 - WM_TOUCH message may cause calls to null if
 touch functions are not properly loaded

Simon Hug

When WIN_WindowProc processes the WM_TOUCH message, it doesn't check if the touch functions have been properly loaded and may call a NULL pointer. It's probably an extremely rare case, but here's a patch that adds some checks anyway.
---
 src/video/windows/SDL_windowsevents.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/video/windows/SDL_windowsevents.c b/src/video/windows/SDL_windowsevents.c
index 926f526f8..afa2d71c1 100644
--- a/src/video/windows/SDL_windowsevents.c
+++ b/src/video/windows/SDL_windowsevents.c
@@ -884,7 +884,7 @@ WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
         break;
 
     case WM_TOUCH:
-        {
+        if (data->videodata->GetTouchInputInfo && data->videodata->CloseTouchInputHandle) {
             UINT i, num_inputs = LOWORD(wParam);
             PTOUCHINPUT inputs = SDL_stack_alloc(TOUCHINPUT, num_inputs);
             if (data->videodata->GetTouchInputInfo((HTOUCHINPUT)lParam, num_inputs, inputs, sizeof(TOUCHINPUT))) {