Microsoft Edge Chakra DictionaryPropertyDescriptor::CopyFrom Failed Copy

Microsoft Edge Chakra has an issue where DictionaryPropertyDescriptor::CopyFrom does not copy all fields.


MD5 | 58ac89a215bdcc730aeb2f04f26ab26d

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Microsoft Edge: Chakra: DictionaryPropertyDescriptor::CopyFrom doesn't copy all fields 

CVE-2018-8291


Here's the method.
    template <typename TPropertyIndex>
    template <typename TPropertyIndexFrom>
    void DictionaryPropertyDescriptor<TPropertyIndex>::CopyFrom(DictionaryPropertyDescriptor<TPropertyIndexFrom>& descriptor)
    {
        this->Attributes = descriptor.Attributes;
        this->Data = (descriptor.Data == DictionaryPropertyDescriptor<TPropertyIndexFrom>::NoSlots) ? NoSlots : descriptor.Data;
        this->Getter = (descriptor.Getter == DictionaryPropertyDescriptor<TPropertyIndexFrom>::NoSlots) ? NoSlots : descriptor.Getter;
        this->Setter = (descriptor.Setter == DictionaryPropertyDescriptor<TPropertyIndexFrom>::NoSlots) ? NoSlots : descriptor.Setter;
        this->IsAccessor = descriptor.IsAccessor;

#if ENABLE_FIXED_FIELDS
        this->IsInitialized = descriptor.IsInitialized;
        this->IsFixed = descriptor.IsFixed;
        this->UsedAsFixed = descriptor.UsedAsFixed;
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