* xdisp.c (compute_stop_pos): Check validity of end_charpos before using it.

Fixes: debbugs:5984

src/ChangeLog

+2011-11-23  Chong Yidong  <cyd@gnu.org>
+
+	* xdisp.c (compute_stop_pos): Check validity of end_charpos before
+	using it (Bug#5984).
+
 2011-11-22  Eli Zaretskii  <eliz@gnu.org>
 
 	* dispnew.c (adjust_glyph_matrix): Don't verify hash code of mode-

src/xdisp.c

@@ -3166,13 +3166,11 @@ compute_stop_pos (struct it *it)
   Lisp_Object object, limit, position;
   EMACS_INT charpos, bytepos;
-  /* If nowhere else, stop at the end.  */
-  it->stop_charpos = it->end_charpos;
-
   if (STRINGP (it->string))
     {
       /* Strings are usually short, so don't limit the search for
 	 properties.  */
+      it->stop_charpos = it->end_charpos;
       object = it->string;
       limit = Qnil;
       charpos = IT_STRING_CHARPOS (*it);
@@ -3182,6 +3180,12 @@ compute_stop_pos (struct it *it)
     {
       EMACS_INT pos;
+      /* If end_charpos is out of range for some reason, such as a
+	 misbehaving display function, rationalize it (Bug#5984).  */
+      if (it->end_charpos > ZV)
+	it->end_charpos = ZV;
+      it->stop_charpos = it->end_charpos;
+
       /* If next overlay change is in front of the current stop pos
 	 (which is IT->end_charpos), stop there.  Note: value of
 	 next_overlay_change is point-max if no overlay change