mdocml: Don't dereference NULL pointers when formatting missing

mdocml: Don't dereference NULL pointers when formatting missing

[schwarze]

Log Message:
-----------
Don't dereference NULL pointers when formatting missing denominators,
subscripts, superscripts, or "from" or "to" arguments.
Found by jsg@ with afl.

Modified Files:
--------------
    mdocml:
        LICENSE
        eqn_term.c

Revision Data
-------------
Index: eqn_term.c
===================================================================
RCS file: /home/cvs/mdocml/mdocml/eqn_term.c,v
retrieving revision 1.7
retrieving revision 1.8
diff -Leqn_term.c -Leqn_term.c -u -p -r1.7 -r1.8
--- eqn_term.c
+++ eqn_term.c
@@ -1,7 +1,7 @@
 /*	$Id$ */
 /*
  * Copyright (c) 2011 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2014 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2014, 2015 Ingo Schwarze <schwarze@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -79,14 +79,17 @@ eqn_box(struct termp *p, const struct eq
 		     bp->pos == EQNPOS_TO) ? "^" : "_");
 		p->flags |= TERMP_NOSPACE;
 		child = child->next;
-		eqn_box(p, child);
-		if (bp->pos == EQNPOS_FROMTO ||
-		    bp->pos == EQNPOS_SUBSUP) {
-			p->flags |= TERMP_NOSPACE;
-			term_word(p, "^");
-			p->flags |= TERMP_NOSPACE;
-			child = child->next;
+		if (child != NULL) {
 			eqn_box(p, child);
+			if (bp->pos == EQNPOS_FROMTO ||
+			    bp->pos == EQNPOS_SUBSUP) {
+				p->flags |= TERMP_NOSPACE;
+				term_word(p, "^");
+				p->flags |= TERMP_NOSPACE;
+				child = child->next;
+				if (child != NULL)
+					eqn_box(p, child);
+			}
 		}
 	} else {
 		child = bp->first;
Index: LICENSE
===================================================================
RCS file: /home/cvs/mdocml/mdocml/LICENSE,v
retrieving revision 1.5
retrieving revision 1.6
diff -LLICENSE -LLICENSE -u -p -r1.5 -r1.6
--- LICENSE
+++ LICENSE
@@ -5,7 +5,7 @@ contained in the mdocml toolkit is prote
 of the following developers:
 
 Copyright (c) 2008-2012, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
-Copyright (c) 2010, 2011, 2012, 2013, 2014 Ingo Schwarze <schwarze@openbsd.org>
+Copyright (c) 2010-2015 Ingo Schwarze <schwarze@openbsd.org>
 Copyright (c) 2009, 2010, 2011, 2012 Joerg Sonnenberger <joerg@netbsd.org>
 Copyright (c) 2013 Franco Fichtner <franco@lastsummer.de>
 Copyright (c) 1999, 2004 Marc Espie <espie@openbsd.org>
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