===================================================================
RCS file: /cvs/mandoc/roff.c,v
retrieving revision 1.288
retrieving revision 1.293
diff -u -p -r1.288 -r1.293
--- mandoc/roff.c	2017/01/12 18:02:20	1.288
+++ mandoc/roff.c	2017/03/09 15:29:35	1.293
@@ -1,4 +1,4 @@
-/*	$Id: roff.c,v 1.288 2017/01/12 18:02:20 schwarze Exp $ */
+/*	$Id: roff.c,v 1.293 2017/03/09 15:29:35 schwarze Exp $ */
 /*
  * Copyright (c) 2008-2012, 2014 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2015, 2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -1226,15 +1226,22 @@ deroff(char **dest, const struct roff_node *n)
 	/* Skip leading whitespace. */
 
 	for (cp = n->string; *cp != '\0'; cp++) {
-		if (cp[0] == '\\' && strchr(" %&0^|~", cp[1]) != NULL)
+		if (cp[0] == '\\' && cp[1] != '\0' &&
+		    strchr(" %&0^|~", cp[1]) != NULL)
 			cp++;
 		else if ( ! isspace((unsigned char)*cp))
 			break;
 	}
 
+	/* Skip trailing backslash. */
+
+	sz = strlen(cp);
+	if (sz > 0 && cp[sz - 1] == '\\')
+		sz--;
+
 	/* Skip trailing whitespace. */
 
-	for (sz = strlen(cp); sz; sz--)
+	for (; sz; sz--)
 		if ( ! isspace((unsigned char)cp[sz-1]))
 			break;
 
@@ -1601,7 +1608,7 @@ roff_parseln(struct roff *r, int ln, struct buf *buf, 
 			return ROFF_IGN;
 		while (buf->buf[pos] != '\0' && buf->buf[pos] != ' ')
 			pos++;
-		while (buf->buf[pos] != '\0' && buf->buf[pos] == ' ')
+		while (buf->buf[pos] == ' ')
 			pos++;
 		return tbl_read(r->tbl, ln, buf->buf, pos);
 	}
@@ -3031,7 +3038,7 @@ roff_userdef(ROFF_ARGS)
 {
 	const char	 *arg[9], *ap;
 	char		 *cp, *n1, *n2;
-	int		  i, ib, ie;
+	int		  expand_count, i, ib, ie;
 	size_t		  asz, rsz;
 
 	/*
@@ -3055,8 +3062,9 @@ roff_userdef(ROFF_ARGS)
 	 */
 
 	buf->sz = strlen(r->current_string) + 1;
-	n1 = cp = mandoc_malloc(buf->sz);
+	n1 = n2 = cp = mandoc_malloc(buf->sz);
 	memcpy(n1, r->current_string, buf->sz);
+	expand_count = 0;
 	while (*cp != '\0') {
 
 		/* Scan ahead for the next argument invocation. */
@@ -3076,6 +3084,20 @@ roff_userdef(ROFF_ARGS)
 		cp -= 2;
 
 		/*
+		 * Prevent infinite recursion.
+		 */
+
+		if (cp >= n2)
+			expand_count = 1;
+		else if (++expand_count > EXPAND_LIMIT) {
+			mandoc_msg(MANDOCERR_ROFFLOOP, r->parse,
+			    ln, (int)(cp - n1), NULL);
+			free(buf->buf);
+			buf->buf = n1;
+			return ROFF_IGN;
+		}
+
+		/*
 		 * Determine the size of the expanded argument,
 		 * taking escaping of quotes into account.
 		 */
@@ -3358,7 +3380,8 @@ roff_strdup(const struct roff *r, const char *p)
 	ssz = 0;
 
 	while ('\0' != *p) {
-		if ('\\' != *p && r->xtab && r->xtab[(int)*p].p) {
+		assert((unsigned int)*p < 128);
+		if ('\\' != *p && r->xtab && r->xtab[(unsigned int)*p].p) {
 			sz = r->xtab[(int)*p].sz;
 			res = mandoc_realloc(res, ssz + sz + 1);
 			memcpy(res + ssz, r->xtab[(int)*p].p, sz);