Issue 5239 - JsValue access crash

libadblockplus-android/jni/JniJsValue.cpp

Index: libadblockplus-android/jni/JniJsValue.cpp
diff --git a/libadblockplus-android/jni/JniJsValue.cpp b/libadblockplus-android/jni/JniJsValue.cpp
index d39645fe400cc06a51ca55a4725f54599ab2fb05..92c4847c6d20e656a1fe140ca439ef1140a26cbe 100644
--- a/libadblockplus-android/jni/JniJsValue.cpp
+++ b/libadblockplus-android/jni/JniJsValue.cpp
@@ -168,7 +168,8 @@ static void JNICALL JniDtor(JNIEnv* env, jclass clazz, jlong 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)