Main: Guards against NULL dereferences (#879)

ExplorerPatcher/dllmain.c

@@ -4624,10 +4624,12 @@ BOOL explorer_SetChildWindowNoActivateHook(HWND hWnd)
     if (!wcscmp(className, L"TrayButton"))
     {
         uintptr_t Instance = *(uintptr_t*)GetWindowLongPtrW(hWnd, 0);
+        if (Instance)
+        {
             uintptr_t TrayButton_GetComponentName = *(INT_PTR(WINAPI**)())(Instance + 304);
             if (!IsBadCodePtr(TrayButton_GetComponentName))
             {
-            wchar_t* wszComponentName = (const WCHAR*)(*(uintptr_t (**)(void))(Instance + 304))();
+                wchar_t* wszComponentName = (const WCHAR*)(*(uintptr_t(**)(void))(Instance + 304))();
                 if (!wcscmp(wszComponentName, L"CortanaButton"))
                 {
                     DWORD dwOldProtect;
@@ -4692,6 +4694,7 @@ BOOL explorer_SetChildWindowNoActivateHook(HWND hWnd)
                 }
             }
         }
+    }
     return SetChildWindowNoActivateFunc(hWnd);
 }
 #endif
@@ -6173,12 +6176,15 @@ void Explorer_RefreshClockHelper(HWND hClockButton)
     // we call v_Initialize because all it does is to query the
     // registry and update the internal state to display seconds or not
     // to get the offset, simply inspect the vtable of ClockButton
+    if (ClockButtonInstance)
+    {
         ((void(*)(void*))(*(INT64*)((*(INT64*)ClockButtonInstance) + 6 * sizeof(uintptr_t))))(ClockButtonInstance); // v_Initialize
         // we need to refresh the button; for the text to actually change, we need to set this:
         // inspect ClockButton::v_OnTimer
         *((BYTE*)ClockButtonInstance + 547) = 1;
         // then, we simply invalidate the area
         InvalidateRect(hClockButton, NULL, TRUE);
+    }
 }
 
 void Explorer_RefreshClock(int unused)
@@ -6229,11 +6235,16 @@ void Explorer_TogglePeopleButton(int unused)
     if (hShellTray_Wnd)
     {
         INT64* CTrayInstance = (BYTE*)(GetWindowLongPtrW(hShellTray_Wnd, 0)); // -> CTray
+        if (CTrayInstance)
+        {
             const unsigned int TRAYUI_OFFSET_IN_CTRAY = 110;
             INT64* TrayUIInstance = *((INT64*)CTrayInstance + TRAYUI_OFFSET_IN_CTRAY);
-
+            if (TrayUIInstance)
+            {
                 ((void(*)(void*))(*(INT64*)((*(INT64*)TrayUIInstance) + 57 * sizeof(uintptr_t))))(TrayUIInstance);
             }
+        }
+    }
 }
 
 void Explorer_ToggleTouchpad(int unused)
@@ -6242,11 +6253,16 @@ void Explorer_ToggleTouchpad(int unused)
     if (hShellTray_Wnd)
     {
         INT64* CTrayInstance = (BYTE*)(GetWindowLongPtrW(hShellTray_Wnd, 0)); // -> CTray
+        if (CTrayInstance)
+        {
             const unsigned int TRAYUI_OFFSET_IN_CTRAY = 110;
             INT64* TrayUIInstance = *((INT64*)CTrayInstance + TRAYUI_OFFSET_IN_CTRAY);
-
+            if (TrayUIInstance)
+            {
                 ((void(*)(void*))(*(INT64*)((*(INT64*)TrayUIInstance) + 60 * sizeof(uintptr_t))))(TrayUIInstance);
             }
+        }
+    }
 }
 #pragma endregion