ensure tag/content_tag escapes " in attribute vals

Many helpers mark content as HTML-safe without escaping double quotes -- including `sanitize`. Regardless of whether or not the attribute values are HTML-escaped, we want to be sure they don't include double quotes, as that can cause XSS issues. For example: `content_tag(:div, "foo", title: sanitize('" onmouseover="alert(1);//'))`

CVE-2016-6316

Author: andrewcarpenter

actionpack/lib/action_view/helpers/tag_helper.rb

@@ -141,20 +141,27 @@ def tag_options(options, escape = true)
                   unless v.is_a?(String) || v.is_a?(Symbol) || v.is_a?(BigDecimal)
                     v = v.to_json
                   end
-                  v = ERB::Util.html_escape(v) if escape
-                  attrs << %(data-#{k.to_s.dasherize}="#{v}")
+                  attrs << tag_option("data-#{k.to_s.dasherize}", v, escape)
                 end
               elsif BOOLEAN_ATTRIBUTES.include?(key)
                 attrs << %(#{key}="#{key}") if value
               elsif !value.nil?
                 final_value = value.is_a?(Array) ? value.join(" ") : value
-                final_value = ERB::Util.html_escape(final_value) if escape
-                attrs << %(#{key}="#{final_value}")
+                attrs << tag_option(key, value, escape)
               end
             end
             " #{attrs.sort * ' '}".html_safe unless attrs.empty?
           end
         end
+
+        def tag_option(key, value, escape)
+          if value.is_a?(Array)
+            value = escape ? safe_join(value, " ") : value.join(" ")
+          else
+            value = escape ? ERB::Util.html_escape(value) : value
+          end
+          %(#{key}="#{value.gsub(/"/, '&quot;'.freeze)}")
+        end
     end
   end
 end

actionpack/test/template/tag_helper_test.rb

@@ -101,6 +101,16 @@ def test_tag_honors_html_safe_for_param_values
     end
   end
 
+  def test_tag_does_not_honor_html_safe_double_quotes_as_attributes
+    assert_dom_equal '<p title="&quot;">content</p>',
+      content_tag('p', "content", title: '"'.html_safe)
+  end
+
+  def test_data_tag_does_not_honor_html_safe_double_quotes_as_attributes
+    assert_dom_equal '<p data-title="&quot;">content</p>',
+      content_tag('p', "content", data: { title: '"'.html_safe })
+  end
+
   def test_skip_invalid_escaped_attributes
     ['&1;', '&#1dfa3;', '& #123;'].each do |escaped|
       assert_equal %(<a href="#{escaped.gsub(/&/, '&amp;')}" />), tag('a', :href => escaped)