Return self when calling #each, #each_pair, and #each_value instead o…

…f the raw @parameters hash

[CVE-2020-8164]

actionpack/lib/action_controller/metal/strong_parameters.rb

@@ -337,6 +337,8 @@ def each_pair(&block)
       @parameters.each_pair do |key, value|
         yield [key, convert_hashes_to_parameters(key, value)]
       end
+
+      self
     end
     alias_method :each, :each_pair
 

actionpack/test/controller/parameters/accessors_test.rb

@@ -20,6 +20,14 @@ class ParametersAccessorsTest < ActiveSupport::TestCase
     )
   end
 
+  test "each returns self" do
+    assert_same @params, @params.each { |_| _ }
+  end
+
+  test "each_pair returns self" do
+    assert_same @params, @params.each_pair { |_| _ }
+  end
+
   test "[] retains permitted status" do
     @params.permit!
     assert_predicate @params[:person], :permitted?