patch 9.0.1992: [security] segfault in exmode

Problem:  segfault in exmode when redrawing
Solution: skip gui_scroll when exmode_active

Signed-off-by: Christian Brabandt <cb@256bit.org>

src/gui.c

@@ -4397,6 +4397,7 @@ gui_do_scrollbar(
  * Scroll a window according to the values set in the globals
  * "current_scrollbar" and "scrollbar_value".
  * Return TRUE if the cursor in the current window moved or FALSE otherwise.
+ * may eventually cause a redraw using updateWindow
  */
     int
 gui_do_scroll(void)
@@ -4416,6 +4417,9 @@ gui_do_scroll(void)
     if (wp == NULL)
 	// Couldn't find window
 	return FALSE;
+    // don't redraw, LineOffset and similar are not valid!
+    if (exmode_active)
+	return FALSE;
 
     /*
      * Compute number of lines to scroll.  If zero, nothing to do.

src/testdir/crash/crash_scrollbar

@@ -0,0 +1,2 @@
+" this goes to insert mode and presses key k_VerScrollbar which may cause a redraw in exmode, which used ot crash Vim
+norm o<><6F>X

src/testdir/test_crash.vim

@@ -72,6 +72,12 @@ func Test_crash1()
     \ '  || echo "crash 8: [OK]" >> X_crash1_result.txt' .. "\<cr>")
   call TermWait(buf, 3000)
 
+  let file = 'crash/crash_scrollbar'
+  let args = printf(cmn_args, vim, file)
+  call term_sendkeys(buf, args ..
+    \ '  && echo "crash 9: [OK]" >> X_crash1_result.txt' .. "\<cr>")
+  call TermWait(buf, 1000)
+
   " clean up
   exe buf .. "bw!"
 
@@ -86,6 +92,7 @@ func Test_crash1()
       \ 'crash 6: [OK]',
       \ 'crash 7: [OK]',
       \ 'crash 8: [OK]',
+      \ 'crash 9: [OK]',
       \ ]
 
   call assert_equal(expected, getline(1, '$'))

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1992,
 /**/
     1991,
 /**/