FileHandler should not be called for files outside the root

FileHandler#matches? should return false for files that are outside the
"root" path.

1 files changed, 12 insertions, 2 deletions

diff --git a/actionpack/lib/action_dispatch/middleware/static.rb b/actionpack/lib/action_dispatch/middleware/static.rb
index e66c21ef85..002bf8b11a 100644
--- a/actionpack/lib/action_dispatch/middleware/static.rb
+++ b/actionpack/lib/action_dispatch/middleware/static.rb
@@ -24,9 +24,19 @@ module ActionDispatch
       path = URI.parser.unescape(path)
       return false unless path.valid_encoding?
 
-      paths = [path, "#{path}#{ext}", "#{path}/index#{ext}"]
+      paths = [path, "#{path}#{ext}", "#{path}/index#{ext}"].map { |v|
+        Rack::Utils.clean_path_info v
+      }
 
-      if match = paths.detect {|p| File.file?(File.join(@root, p)) }
+      if match = paths.detect { |p|
+        path = File.join(@root, p)
+        begin
+          File.file?(path) && File.readable?(path)
+        rescue SystemCallError
+          false
+        end
+
+      }
         return ::Rack::Utils.escape(match)
       end
     end