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From d4a53b2e02106c6734bbfea2a0e209febd5f36bd Mon Sep 17 00:00:00 2001
From: Tobias Kraze <tobias@kraze.eu>
Date: Fri, 8 Feb 2013 12:52:10 +0100
Subject: [PATCH] fix serialization vulnerability
---
.../lib/active_record/attribute_methods.rb | 17 ++++++++++++++++-
activerecord/test/cases/base_test.rb | 6 ++++++
2 files changed, 22 insertions(+), 1 deletion(-)
--- a/activerecord/lib/active_record/attribute_methods.rb
+++ b/activerecord/lib/active_record/attribute_methods.rb
@@ -80,7 +80,9 @@ module ActiveRecord
end
unless instance_method_already_implemented?("#{name}=")
- if create_time_zone_conversion_attribute?(name, column)
+ if self.serialized_attributes[name]
+ define_write_method_for_serialized_attribute(name)
+ elsif create_time_zone_conversion_attribute?(name, column)
define_write_method_for_time_zone_conversion(name)
else
define_write_method(name.to_sym)
@@ -184,6 +186,19 @@ module ActiveRecord
def define_write_method(attr_name)
evaluate_attribute_method attr_name, "def #{attr_name}=(new_value);write_attribute('#{attr_name}', new_value);end", "#{attr_name}="
end
+
+ # Defined for all serialized attributes. Disallows assigning already serialized YAML.
+ def define_write_method_for_serialized_attribute(attr_name)
+ method_body = <<-EOV
+ def #{attr_name}=(value)
+ if value.is_a?(String) and value =~ /^---/
+ raise ActiveRecordError, "You tried to assign already serialized content to #{attr_name}. This is disabled due to security issues."
+ end
+ write_attribute(:#{attr_name}, value)
+ end
+ EOV
+ evaluate_attribute_method attr_name, method_body, "#{attr_name}="
+ end
# Defined for all +datetime+ and +timestamp+ attributes when +time_zone_aware_attributes+ are enabled.
# This enhanced write method will automatically convert the time passed to it to the zone stored in Time.zone.
--- a/activerecord/test/cases/base_test.rb
+++ b/activerecord/test/cases/base_test.rb
@@ -1516,6 +1516,12 @@ class BasicsTest < ActiveRecord::TestCas
assert_nil topic.content
end
+ def test_should_raise_exception_on_assigning_already_serialized_content
+ topic = Topic.new
+ serialized_content = %w[foo bar].to_yaml
+ assert_raise(ActiveRecord::ActiveRecordError) { topic.content = serialized_content }
+ end
+
def test_should_raise_exception_on_serialized_attribute_with_type_mismatch
myobj = MyObject.new('value1', 'value2')
topic = Topic.new(:content => myobj)
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