Possible NRE in BinaryFormatterWriter.WriteObject( ... ) method

[buyaa-n]

While annotating System.Runtime.Serialization.Formatters for nullable found a method called with null reference but used without null check causing NRE. In below method typeNameInfo parameter explicitly called with null: _serWriter.WriteObject(typeNameInfo, null, numItems, memberNames, memberTypes, memberObjectInfos); which referenced twice within the method objectName = typeNameInfo.NIname and else if (!typeNameInfo._transmitTypeOnObject). https://github.com/dotnet/corefx/blob/master/src/System.Runtime.Serialization.Formatters/src/System/Runtime/Serialization/Formatters/Binary/BinaryObjectWriter.cs#L230

internal void WriteObject(NameInfo nameInfo, NameInfo typeNameInfo, int numMembers, string[] memberNames, Type[] memberTypes, WriteObjectInfo[] memberObjectInfos)
{
    InternalWriteItemNull();
    int assemId;
    int objectId = (int)nameInfo._objectId;

    string objectName = objectId < 0 ?
    objectName = typeNameInfo.NIname : // Nested Object
    objectName = nameInfo.NIname; // Non-Nested

    if (_objectMapTable == null)
    {
         _objectMapTable = new Dictionary<string, ObjectMapInfo>();
    }

    ObjectMapInfo objectMapInfo;
    if (_objectMapTable.TryGetValue(objectName, out objectMapInfo) &&
          objectMapInfo.IsCompatible(numMembers, memberNames, memberTypes))
   {
        // Object
        if (_binaryObject == null)
        {
            _binaryObject = new BinaryObject();
        }

        _binaryObject.Set(objectId, objectMapInfo._objectId);
        _binaryObject.Write(this);
    }
    else if (!typeNameInfo._transmitTypeOnObject)
    {
        ...
    }

[joperezr]

@buyaa-n do we have to fix this for 5.0?

[buyaa-n]

@joperezr I was not really planning to fix it, I would let the area owners fix it.

Oops sorry, I thought i put 5.0 so changed it, now i see you put 5.0, reverting to 5.0 back

[buyaa-n]

Sorry @joperezr misread your question, i think it would be good to have it fixed in 5.0, but as BinaryFormatter is being obsoleted now not sure if we would/should fix it CC @GrabYourPitchforks

[GrabYourPitchforks]

We're no longer investing in this type, including closing any reported issues as "won't fix". I recommend closing this issue. But neat find! :)

[buyaa-n]

Thank you @GrabYourPitchforks closing with won't fix, obsoleted