1 files changed, 15 insertions, 0 deletions
diff --git a/actionpack/lib/action_dispatch/request/utils.rb b/actionpack/lib/action_dispatch/request/utils.rb
index a8151a8224..bb3df3c311 100644
--- a/actionpack/lib/action_dispatch/request/utils.rb
+++ b/actionpack/lib/action_dispatch/request/utils.rb
@@ -13,6 +13,21 @@ module ActionDispatch
         end
       end
 
+      def self.check_param_encoding(params)
+        case params
+        when Array
+          params.each { |element| check_param_encoding(element) }
+        when Hash
+          params.each_value { |value| check_param_encoding(value) }
+        when String
+          unless params.valid_encoding?
+            # Raise Rack::Utils::InvalidParameterError for consistency with Rack.
+            # ActionDispatch::Request#GET will re-raise as a BadRequest error.
+            raise Rack::Utils::InvalidParameterError, "Non UTF-8 value: #{params}"
+          end
+        end
+      end
+
       class ParamEncoder # :nodoc:
         # Convert nested Hash to HashWithIndifferentAccess.
         #