Deep Munge the parameters for GET and POST

The previous implementation of this functionality could be accidentally
subverted by instantiating a raw Rack::Request before the first Rails::Request
was constructed.

Fixes CVE-2013-6417

actionpack/lib/action_dispatch/http/request.rb

@@ -271,7 +271,7 @@ module ActionDispatch
 
     # Override Rack's GET method to support indifferent access
     def GET
-      @env["action_dispatch.request.query_parameters"] ||= (normalize_encode_params(super) || {})
+      @env["action_dispatch.request.query_parameters"] ||= deep_munge((normalize_encode_params(super) || {}))
     rescue TypeError => e
       raise ActionController::BadRequest.new(:query, e)
     end
@@ -279,7 +279,7 @@ module ActionDispatch
 
     # Override Rack's POST method to support indifferent access
     def POST
-      @env["action_dispatch.request.request_parameters"] ||= (normalize_encode_params(super) || {})
+      @env["action_dispatch.request.request_parameters"] ||= deep_munge((normalize_encode_params(super) || {}))
     rescue TypeError => e
       raise ActionController::BadRequest.new(:request, e)
     end

actionpack/test/dispatch/request/query_string_parsing_test.rb

@@ -11,6 +11,17 @@ class QueryStringParsingTest < ActionDispatch::IntegrationTest
       head :ok
     end
   end
+  class EarlyParse
+    def initialize(app)
+      @app = app
+    end
+
+    def call(env)
+      # Trigger a Rack parse so that env caches the query params
+      Rack::Request.new(env).params
+      @app.call(env)
+    end
+  end
 
   def teardown
     TestController.last_query_parameters = nil
@@ -131,6 +142,10 @@ class QueryStringParsingTest < ActionDispatch::IntegrationTest
         set.draw do
           get ':action', :to => ::QueryStringParsingTest::TestController
         end
+        @app = self.class.build_app(set) do |middleware|
+          middleware.use(EarlyParse)
+        end
+
 
         get "/parse", actual
         assert_response :ok