marshal.c: fix infinite recursion

* marshal.c (check_userdump_arg): marshal_dump should not return
  an instance of the same class, otherwise it causes infinite
  recursion.  [ruby-core:78289] [Bug #12974]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@56894 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 12 insertions, 0 deletions

diff --git a/test/ruby/test_marshal.rb b/test/ruby/test_marshal.rb
index d21ab66ffd..bc22b5fd3a 100644
--- a/test/ruby/test_marshal.rb
+++ b/test/ruby/test_marshal.rb
@@ -757,4 +757,16 @@ class TestMarshal < Test::Unit::TestCase
     end
     assert_equal(obj, Marshal.load(dump))
   end
+
+  class Bug12974
+    def marshal_dump
+      dup
+    end
+  end
+
+  def test_marshal_dump_recursion
+    assert_raise_with_message(RuntimeError, /same class instance/) do
+      Marshal.dump(Bug12974.new)
+    end
+  end
 end