merge revision(s) 56938: [Backport #12988]

	Stop reading past the end of `ivptr` array

	If you have code like this:

	```ruby
	class A
  def initialize
    @a = nil
    @b = nil
    @c = nil
    @d = nil
    @e = nil
  end
	end

	x = A.new
	y = x.clone
	100.times { |z| x.instance_variable_set(:"@foo#{z}", nil) }
	puts y.inspect
	```

	`x` and `y` will share `iv_index_tbl` hashes.  However, the size of the
	hash will grow larger than the number if entries in `ivptr` in `y`.
	Before this commit, `rb_ivar_count` would use the size of the hash to
	determine how far to read in to the array, but this means that it could
	read past the end of the array and cause the program to segv

	[ruby-core:78403]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_2@57214 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 7 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index feb588e0bd..960e8cd7d4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Dec 27 19:34:47 2016  Aaron Patterson <tenderlove@ruby-lang.org>
+
+	* variable.c (rb_ivar_count): stop reading past the end of ivptr array.
+	  [Bug #12988]
+
 Tue Dec 27 19:32:03 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* thread.c (rb_thread_s_abort_exc, rb_thread_s_abort_exc_set):
diff --git a/variable.c b/variable.c
index 691af04d3c..290a10b235 100644
--- a/variable.c
+++ b/variable.c
@@ -1322,7 +1322,7 @@ rb_ivar_count(VALUE obj)
     switch (BUILTIN_TYPE(obj)) {
       case T_OBJECT:
 	if ((tbl = ROBJECT_IV_INDEX_TBL(obj)) != 0) {
-	    st_index_t i, count, num = tbl->num_entries;
+	    st_index_t i, count, num = ROBJECT_NUMIV(obj);
 	    const VALUE *const ivptr = ROBJECT_IVPTR(obj);
 	    for (i = count = 0; i < num; ++i) {
 		if (ivptr[i] != Qundef) {
diff --git a/version.h b/version.h
index 536a7bd8cd..b090b5c7f3 100644
--- a/version.h
+++ b/version.h
@@ -1,6 +1,6 @@
 #define RUBY_VERSION "2.2.7"
 #define RUBY_RELEASE_DATE "2016-12-27"
-#define RUBY_PATCHLEVEL 404
+#define RUBY_PATCHLEVEL 405
 
 #define RUBY_RELEASE_YEAR 2016
 #define RUBY_RELEASE_MONTH 12