ruby.c: fix pointer overrun

* ruby.c (proc_options): fix pointer overrun. do not advance argv
  until it is valid.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@52697 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Sat Nov 21 18:41:53 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ruby.c (proc_options): fix pointer overrun. do not advance argv
+	  until it is valid.
+
 Sat Nov 21 13:59:09 2015  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* ext/digest/sha1/extconf.rb: OpenSSL's struct name for SHA1 is

ruby.c

@@ -1088,7 +1088,7 @@ proc_options(long argc, char **argv, struct cmdline_options *opt, int envopt)
 	    (((allow_envopt) || !envopt) ? (void)0 : \
 	     rb_raise(rb_eRuntimeError, "invalid switch in RUBYOPT: --" name))
 #	define need_argument(name, s, needs_arg) \
-	    ((*(s)++ ? !*(s) : (!--argc || !((s) = *++argv))) && (needs_arg) ? \
+	    ((*(s) ? !*++(s) : (!argc || !((s) = argv[1]) || (--argc, ++argv, 0))) && (needs_arg) ? \
 	     rb_raise(rb_eRuntimeError, "missing argument for --" name) \
 	     : (void)0)
 #	define is_option_with_arg(name, allow_hyphen, allow_envopt)	\