Add new code to recv_group_name() too.

uidlist.c

@@ -390,12 +390,18 @@ gid_t recv_group_name(int f, gid_t gid, uint16 *flags_ptr)
 {
 	struct idlist *node;
 	int len = read_byte(f);
-	char *name = new_array(char, len+1);
-	read_sbuf(f, name, len);
-	if (numeric_ids < 0) {
-		free(name);
+	char *name;
+
+	if (len) {
+		name = new_array(char, len+1);
+		read_sbuf(f, name, len);
+		if (numeric_ids < 0) {
+			free(name);
+			name = NULL;
+		}
+	} else
 		name = NULL;
-	}
+
 	node = recv_add_id(&gidlist, gidmap, gid, name); /* node keeps name's memory */
 	if (flags_ptr && node->flags & FLAG_SKIP_GROUP)
 		*flags_ptr |= FLAG_SKIP_GROUP;