01/01: [WIN32K:NTUSER] Fix WIN32K BSOD mentioned in CORE-15027

[Joachim Henze]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=ef016bfe0a9dc3cc792467...

commit ef016bfe0a9dc3cc7924671277b44884e39d89d5
Author:     Joachim Henze [e-mail]
AuthorDate: Fri Sep 21 03:04:31 2018 +0200
Commit:     Joachim Henze [e-mail]
CommitDate: Fri Sep 21 03:04:31 2018 +0200

[WIN32K:NTUSER] Fix WIN32K BSOD mentioned in CORE-15027

Fixes accessing nullptr / invalid handle in Window->SystemMenu
    I could trigger this occasionally when moving Opera 12.18 window
    in front of Spotify 1.0.29.92 window.

Fix was:
    authored by Thomas Faber (Thank you!)
    tested by me
    reviewed by James Tabor
---
 win32ss/user/ntuser/menu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/win32ss/user/ntuser/menu.c b/win32ss/user/ntuser/menu.c
index 1e29d1d178..48d9dcc169 100644
--- a/win32ss/user/ntuser/menu.c
+++ b/win32ss/user/ntuser/menu.c
@@ -5181,7 +5181,7 @@ IntGetSystemMenu(PWND Window, BOOL bRevert)
    else
    {
       Menu = Window->SystemMenu ? UserGetMenuObject(Window->SystemMenu) : NULL;
-      if ((!Window->SystemMenu || Menu->fFlags & MNF_SYSDESKMN) && Window->style & WS_SYSMENU)
+      if ((!Menu || Menu->fFlags & MNF_SYSDESKMN) && Window->style & WS_SYSMENU)
       {
          Menu = MENU_GetSystemMenu(Window, NULL);
          Window->SystemMenu = Menu ? UserHMGetHandle(Menu) : NULL;