* lib/rexml/entity.rb: keep the entity size within the limitation.

reported by Willis Vandevanter <will@silentrobots.com> and
  patched by nahi.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48161 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,9 @@
+Mon Oct 27 20:13:37 2014  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* lib/rexml/entity.rb: keep the entity size within the limitation.
+	  reported by Willis Vandevanter <will@silentrobots.com> and
+	  patched by nahi.
+
 Mon Oct 27 17:17:24 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* proc.c (method_proc): the receiver of binding from method should

lib/rexml/entity.rb

@@ -138,8 +138,14 @@ module REXML
         matches = @value.scan(PEREFERENCE_RE)
         rv = @value.clone
         if @parent
+          sum = 0
           matches.each do |entity_reference|
             entity_value = @parent.entity( entity_reference[0] )
+            if sum + entity_value.bytesize > Security.entity_expansion_text_limit
+              raise "entity expansion has grown too large"
+            else
+              sum += entity_value.bytesize
+            end
             rv.gsub!( /%#{entity_reference.join};/um, entity_value )
           end
         end

test/rexml/test_document.rb

@@ -46,6 +46,20 @@ EOF
 <member>
 &a;
 </member>
+EOF
+
+    XML_WITH_NESTED_PARAMETER_ENTITY = <<EOF
+<!DOCTYPE root [
+  <!ENTITY % a "BOOM.BOOM.BOOM.BOOM.BOOM.BOOM.BOOM.BOOM.BOOM.">
+  <!ENTITY % b "%a;%a;%a;%a;%a;%a;%a;%a;%a;%a;%a;%a;%a;%a;%a;">
+  <!ENTITY % c "%b;%b;%b;%b;%b;%b;%b;%b;%b;%b;%b;%b;%b;%b;%b;">
+  <!ENTITY % d "%c;%c;%c;%c;%c;%c;%c;%c;%c;%c;%c;%c;%c;%c;%c;">
+  <!ENTITY % e "%d;%d;%d;%d;%d;%d;%d;%d;%d;%d;%d;%d;%d;%d;%d;">
+  <!ENTITY % f "%e;%e;%e;%e;%e;%e;%e;%e;%e;%e;%e;%e;%e;%e;%e;">
+  <!ENTITY % g "%f;%f;%f;%f;%f;%f;%f;%f;%f;%f;%f;%f;%f;%f;%f;">
+  <!ENTITY test "test %g;">
+]>
+<cd></cd>
 EOF
 
     XML_WITH_4_ENTITY_EXPANSION = <<EOF
@@ -86,6 +100,19 @@ EOF
       REXML::Security.entity_expansion_limit = 10000
     end
 
+    def test_entity_expansion_limit_for_parameter_entity
+      assert_raise(REXML::ParseException) do
+        REXML::Document.new(XML_WITH_NESTED_PARAMETER_ENTITY)
+      end
+      REXML::Security.entity_expansion_limit = 100
+      assert_equal(100, REXML::Security.entity_expansion_limit)
+      assert_raise(REXML::ParseException) do
+        REXML::Document.new(XML_WITH_NESTED_PARAMETER_ENTITY)
+      end
+    ensure
+      REXML::Security.entity_expansion_limit = 10000
+    end
+
     def test_tag_in_cdata_with_not_ascii_only_but_ascii8bit_encoding_source
       tag = "<b>...</b>"
       message = "こんにちは、世界！" # Hello world! in Japanese

test/rexml/test_entity.rb

@@ -123,6 +123,22 @@ module REXMLTests
       end
     end
 
+    def test_entity_string_limit_for_parameter_entity
+      template = '<!DOCTYPE bomb [ <!ENTITY % a "^" > <!ENTITY bomb "$" > ]><root/>'
+      len      = 5120 # 5k per entity
+      template.sub!(/\^/, "B" * len)
+
+      # 10k is OK
+      entities = '%a;' * 2 # 5k entity * 2 = 10k
+      REXML::Document.new(template.sub(/\$/, entities))
+
+      # above 10k explodes
+      entities = '%a;' * 3 # 5k entity * 2 = 15k
+      assert_raises(REXML::ParseException) do
+        REXML::Document.new(template.sub(/\$/, entities))
+      end
+    end
+
     def test_raw
       source = '<!DOCTYPE foo [
 <!ENTITY ent "replace">