use secure string comparisons for basic auth username / password

this will avoid timing attacks against applications that use basic auth.

CVE-2015-7576

1 files changed, 6 insertions, 1 deletions

diff --git a/actionpack/lib/action_controller/metal/http_authentication.rb b/actionpack/lib/action_controller/metal/http_authentication.rb
index 2ac6e37e34..35be6d9300 100644
--- a/actionpack/lib/action_controller/metal/http_authentication.rb
+++ b/actionpack/lib/action_controller/metal/http_authentication.rb
@@ -1,4 +1,5 @@
 require 'base64'
+require 'active_support/security_utils'
 
 module ActionController
   # Makes it dead easy to do HTTP Basic, Digest and Token authentication.
@@ -68,7 +69,11 @@ module ActionController
           def http_basic_authenticate_with(options = {})
             before_action(options.except(:name, :password, :realm)) do
               authenticate_or_request_with_http_basic(options[:realm] || "Application") do |name, password|
-                name == options[:name] && password == options[:password]
+                # This comparison uses & so that it doesn't short circuit and
+                # uses `variable_size_secure_compare` so that length information
+                # isn't leaked.
+                ActiveSupport::SecurityUtils.variable_size_secure_compare(name, options[:name]) &
+                  ActiveSupport::SecurityUtils.variable_size_secure_compare(password, options[:password])
               end
             end
           end