Merge branch 'master-security'

* master-security:
  Ensure [] respects the status of the buffer.
  delete vulnerable AS::SafeBuffer#[]
  use AS::SafeBuffer#clone_empty for flushing the output_buffer
  add AS::SafeBuffer#clone_empty
  fix output safety issue with select options

Conflicts:
	actionpack/lib/action_view/helpers/tags/base.rb

Author: tenderlove

actionpack/lib/action_view/helpers/capture_helper.rb

@@ -215,7 +215,7 @@ def with_output_buffer(buf = nil) #:nodoc:
       def flush_output_buffer #:nodoc:
         if output_buffer && !output_buffer.empty?
           response.body_parts << output_buffer
-          self.output_buffer = output_buffer[0,0]
+          self.output_buffer = output_buffer.respond_to?(:clone_empty) ? output_buffer.clone_empty : output_buffer[0, 0]
           nil
         end
       end

actionpack/lib/action_view/helpers/tags/base.rb

@@ -133,12 +133,11 @@ def select_content_tag(option_tags, options, html_options)
 
         def add_options(option_tags, options, value = nil)
           if options[:include_blank]
-            include_blank = options[:include_blank] if options[:include_blank].kind_of?(String)
-            option_tags = content_tag(:option, include_blank, :value => '').safe_concat("\n").safe_concat(option_tags)
+            option_tags = content_tag('option', options[:include_blank].kind_of?(String) ? options[:include_blank] : nil, :value => '') + "\n" + option_tags
           end
           if value.blank? && options[:prompt]
             prompt = options[:prompt].kind_of?(String) ? options[:prompt] : I18n.translate('helpers.select.prompt', :default => 'Please select')
-            option_tags = content_tag(:option, prompt, :value => '').safe_concat("\n").safe_concat(option_tags)
+            option_tags = content_tag('option', prompt, :value => '') + "\n" + option_tags
           end
           option_tags
         end

actionpack/test/template/form_options_helper_test.rb

@@ -509,7 +509,7 @@ def @post.to_param; 108; end
 
   def test_select_under_fields_for_with_string_and_given_prompt
     @post = Post.new
-    options = "<option value=\"abe\">abe</option><option value=\"mus\">mus</option><option value=\"hest\">hest</option>"
+    options = "<option value=\"abe\">abe</option><option value=\"mus\">mus</option><option value=\"hest\">hest</option>".html_safe
 
     output_buffer = fields_for :post, @post do |f|
       concat f.select(:category, options, :prompt => 'The prompt')
@@ -665,6 +665,13 @@ def test_select_with_index_option
     )
   end
 
+  def test_select_escapes_options
+    assert_dom_equal(
+      '<select id="post_title" name="post[title]">&lt;script&gt;alert(1)&lt;/script&gt;</select>',
+      select('post', 'title', '<script>alert(1)</script>')
+    )
+  end
+
   def test_select_with_selected_nil
     @post = Post.new
     @post.category = "<mus>"

activesupport/lib/active_support/core_ext/string/output_safety.rb

@@ -103,29 +103,41 @@ def initialize
       end
     end
 
-    def[](*args)
-      new_safe_buffer = super
-      new_safe_buffer.instance_eval { @dirty = false }
-      new_safe_buffer
+    def [](*args)
+      return super if args.size < 2
+
+      if html_safe?
+        new_safe_buffer = super
+        new_safe_buffer.instance_eval { @html_safe = true }
+        new_safe_buffer
+      else
+        to_str[*args]
+      end
     end
 
     def safe_concat(value)
-      raise SafeConcatError if dirty?
+      raise SafeConcatError unless html_safe?
       original_concat(value)
     end
 
     def initialize(*)
-      @dirty = false
+      @html_safe = true
       super
     end
 
     def initialize_copy(other)
       super
-      @dirty = other.dirty?
+      @html_safe = other.html_safe?
+    end
+
+    def clone_empty
+      new_safe_buffer = self[0, 0]
+      new_safe_buffer.instance_variable_set(:@dirty, @dirty)
+      new_safe_buffer
     end
 
     def concat(value)
-      if dirty? || value.html_safe?
+      if !html_safe? || value.html_safe?
         super(value)
       else
         super(ERB::Util.h(value))
@@ -138,7 +150,7 @@ def +(other)
     end
 
     def html_safe?
-      !dirty?
+      defined?(@html_safe) && @html_safe
     end
 
     def to_s
@@ -161,18 +173,12 @@ def #{unsafe_method}(*args, &block)       # def capitalize(*args, &block)
           end                                       # end
 
           def #{unsafe_method}!(*args)              # def capitalize!(*args)
-            @dirty = true                           #   @dirty = true
+            @html_safe = false                      #   @html_safe = false
             super                                   #   super
           end                                       # end
         EOT
       end
     end
-
-    protected
-
-    def dirty?
-      @dirty
-    end
   end
 end
 

activesupport/test/safe_buffer_test.rb

@@ -84,13 +84,13 @@ def test_titleize
     assert_equal "hello<>", clean + @buffer
   end
 
-  test "Should concat as a normal string when dirty" do
+  test "Should concat as a normal string when safe" do
     clean = "hello".html_safe
     @buffer.gsub!('', '<>')
     assert_equal "<>hello", @buffer + clean
   end
 
-  test "Should preserve dirty? status on copy" do
+  test "Should preserve html_safe? status on copy" do
     @buffer.gsub!('', '<>')
     assert !@buffer.dup.html_safe?
   end
@@ -102,20 +102,42 @@ def test_titleize
     assert_equal "<script>", result_buffer
   end
 
-  test "Should raise an error when safe_concat is called on dirty buffers" do
+  test "Should raise an error when safe_concat is called on unsafe buffers" do
     @buffer.gsub!('', '<>')
     assert_raise ActiveSupport::SafeBuffer::SafeConcatError do
       @buffer.safe_concat "BUSTED"
     end
   end
 
-  test "should not fail if the returned object is not a string" do
+  test "Should not fail if the returned object is not a string" do
     assert_kind_of NilClass, @buffer.slice("chipchop")
   end
 
-  test "Should initialize @dirty to false for new instance when sliced" do
-    dirty = @buffer[0,0].send(:dirty?)
-    assert_not_nil dirty
-    assert !dirty
+  test "clone_empty returns an empty buffer" do
+    assert_equal '', ActiveSupport::SafeBuffer.new('foo').clone_empty
+  end
+
+  test "clone_empty keeps the original dirtyness" do
+    assert @buffer.clone_empty.html_safe?
+    assert !@buffer.gsub!('', '').clone_empty.html_safe?
+  end
+
+  test "Should be safe when sliced if original value was safe" do
+    new_buffer = @buffer[0,0]
+    assert_not_nil new_buffer
+    assert new_buffer.html_safe?, "should be safe"
+  end
+
+  test "Should continue unsafe on slice" do
+    x = 'foo'.html_safe.gsub!('f', '<script>alert("lolpwnd");</script>')
+
+    # calling gsub! makes the dirty flag true
+    assert !x.html_safe?, "should not be safe"
+
+    # getting a slice of it
+    y = x[0..-1]
+
+    # should still be unsafe
+    assert !y.html_safe?, "should not be safe"
   end
 end