Issue 5175 - Reject element hiding filter with empty domain names

compiled/filter/Filter.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 #include "Filter.h"
 #include "CommentFilter.h"
 #include "InvalidFilter.h"
 #include "RegExpFilter.h"
 #include "BlockingFilter.h"
 #include "WhitelistFilter.h"
 #include "ElemHideBase.h"
 #include "ElemHideFilter.h"
 #include "ElemHideException.h"
 #include "ElemHideEmulationFilter.h"
 #include "../StringMap.h"
+
+ABP_NS_USING
 
 namespace
 {
   StringMap<Filter*> knownFilters(8192);
 
   void NormalizeWhitespace(DependentString& text)
   {
     String::size_type start = 0;
     String::size_type end = text.length();
 
@@ skipping 58 matching lines @@
   if (text.empty())
     return nullptr;
 
   // Parsing also normalizes the filter text, so it has to be done before the
   // lookup in knownFilters.
   union
   {
     RegExpFilterData regexp;
     ElemHideData elemhide;
   } data;
+  bool needConversion = false;
   ParsedDomains parsedDomains;
   DependentString error;
 
   Filter::Type type = CommentFilter::Parse(text);
   if (type == Filter::Type::UNKNOWN)
-    type = ElemHideBase::Parse(text, error, data.elemhide, parsedDomains);
+    type = ElemHideBase::Parse(text, error, data.elemhide, needConversion, parsedDomains);
   if (type == Filter::Type::UNKNOWN)
     type = RegExpFilter::Parse(text, error, data.regexp);
+
+  if (needConversion)
+    text = ElemHideBase::ConvertFilter(text, data.elemhide.mSelectorStart);
+
+  // At that point we failed the conversion.
+  if (text.empty())
+    return nullptr;
 
   auto knownFilter = knownFilters.find(text);
   if (knownFilter)
   {
     knownFilter->second->AddRef();
     return knownFilter->second;
   }
 
   FilterPtr filter;
   switch (type)
   {
     case CommentFilter::classType:
       filter = FilterPtr(new CommentFilter(text), false);
       break;
     case InvalidFilter::classType:
       filter = FilterPtr(new InvalidFilter(text, error), false);
       break;
     case BlockingFilter::classType:
       filter = FilterPtr(new BlockingFilter(text, data.regexp), false);
       break;
     case WhitelistFilter::classType:
       filter = FilterPtr(new WhitelistFilter(text, data.regexp), false);
       break;
     case ElemHideFilter::classType:
       filter = FilterPtr(new ElemHideFilter(text, data.elemhide,
         parsedDomains), false);
       break;
     case ElemHideException::classType:
-      filter = FilterPtr(new ElemHideException(text, data.elemhide,
-        parsedDomains), false);
+      filter = FilterPtr(new ElemHideException(text, data.elemhide, parsedDomains), false);
       break;
     case ElemHideEmulationFilter::classType:
-      filter = FilterPtr(new ElemHideEmulationFilter(text, data.elemhide,
-        parsedDomains), false);
+      filter = FilterPtr(new ElemHideEmulationFilter(text, data.elemhide, parsedDomains), false);
       if (static_cast<ElemHideEmulationFilter*>(filter.get())->IsGeneric())
         filter = FilterPtr(new InvalidFilter(text, u"filter_elemhideemulation_nodomain"_str), false);
       break;
     default:
       // This should never happen but just in case
       return nullptr;
   }
 
-  // This is a hack: we looked up the entry using text but create it using
-  // filter->mText. This works because both are equal at this point. However,
-  // text refers to a temporary buffer which will go away.
   enter_context("Adding to known filters");
-  knownFilter.assign(filter->mText, filter.get());
+  if (text != filter->mText)
+    knownFilters[filter->mText] = filter.get();
+  else
+    // This is a hack: we looked up the entry using text but create it using
+    // filter->mText. This works because both are equal at this point. However,
+    // text refers to a temporary buffer which will go away.
+    knownFilter.assign(filter->mText, filter.get());
   exit_context();
 
   return filter.release();
 }