Issue 5239 - JsValue access crash

libadblockplus-android/jni/JniJsValue.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2017 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
@@ skipping 149 matching lines @@
   }
   CATCH_THROW_AND_RETURN(env, 0)
 }
 
 static void JNICALL JniDtor(JNIEnv* env, jclass clazz, jlong ptr)
 {
   delete JniLongToTypePtr<AdblockPlus::JsValue>(ptr);
 }
 
 jobject NewJniJsValue(JNIEnv* env, AdblockPlus::JsValue&& jsValue, jclass jsValueClassArg)
 {

[sergei, 2017/05/12 15:38:07]

I thought about adding some static_assert like below for 64 bit platforms but it
seems we are not building for 64 bit platforms
static_assert(reinterpret_cast<void*>(static_cast<jlong>(reinterpret_cast<uintptr_t>((void*)0xAFFFFFFFFFFFFFFF)))
== (void*)0xAFFFFFFFFFFFFFFF, "Conversion is invalid for 64 bits");

which is basically repeating our operations
originalPointer = (void*)0xAFFFFFFFFFFFFFFF
here we do
pHere = static_cast<jlong>(reinterpret_cast<uintptr_t>(originalPointer))
then in JniLongToTypePtr
ptrValue = reinterpret_cast<void*>(pHere)
and ptrValue should be equal to originalPointer.

Maybe we could put at least
static_assert(sizeof(jlong) >= sizeof(uintptr_t), "jlong should be enough large
to keep positive uintptr_t");
pay attention that currently sizeof(jlong) > sizeof(uintptr_t) always, and
sizeof(jlong) == sizeof(uintptr_t) only on 64 bits.

-  return env->NewObject(jsValueClass->Get(), jsValueCtor, new AdblockPlus::JsValue(std::move(jsValue)));
+  auto pJsValue = reinterpret_cast<uintptr_t>(new AdblockPlus::JsValue(std::move(jsValue)));
+  return env->NewObject(jsValueClass->Get(), jsValueCtor, static_cast<jlong>(pJsValue));
 }
 
 AdblockPlus::JsValue* JniGetJsValuePtr(jlong ptr)
 {
   return JniLongToTypePtr<AdblockPlus::JsValue>(ptr);
 }
 
 AdblockPlus::JsValue& JniGetJsValue(jlong ptr)
 {
   return *JniLongToTypePtr<AdblockPlus::JsValue>(ptr);
@@ skipping 37 matching lines @@
   { (char*)"asBoolean", (char*)"(J)Z", (void*)JniAsBoolean },
   { (char*)"asList", (char*)"(J)Ljava/util/List;", (void*)JniAsList },
   { (char*)"getProperty", (char*)"(JLjava/lang/String;)" TYP("JsValue"), (void*)JniGetProperty },
   { (char*)"dtor", (char*)"(J)V", (void*)JniDtor }
 };
 
 extern "C" JNIEXPORT void JNICALL Java_org_adblockplus_libadblockplus_JsValue_registerNatives(JNIEnv *env, jclass clazz)
 {
   env->RegisterNatives(clazz, methods, sizeof(methods) / sizeof(methods[0]));
 }