Problems using whitemagic. Trying to delegate a function.

[FenixTX2]

Hi,

I'm attempting to delegate a function with the help of whitemagic.
Problem is, it keeps throwing exceptions.

The first happens almost randomly.
This code below will occasionally throw "InvalidFunctionPointerInDelegate was detected" with reference to "function pointer 0x65ec30"

_getName = m.RegisterDelegate<GetNameDelegate>(GetVFunc(VFTableIndex.GetName);

But the real killer comes from the code below.

return Marshal.PtrToStringAnsi(_getName((IntPtr)BaseAddress));

The delegate function throws "AccesViolationException was unhandled 'Attempted to read or write protected memory. This is often an indication that other memory is corrupt.'"

Has anyone any ideas how to solve this?

[MaiN]

[UnmanagedFunctionPointer(CallingConvention.ThisCall)]
private delegate IntPtr GetObjectNameDelegate(IntPtr baseAddress);
private static GetObjectNameDelegate GetObjectNameHandler;

public string Name
{
    get
    {
        if (GetObjectNameHandler == null)
        {
            GetObjectNameHandler = GetVirtualFunction<GetObjectNameDelegate>(Offsets.VirtualFunctions.GetName);
        }

        IntPtr objNamePtr = GetObjectNameHandler(BaseAddress);
        if (objNamePtr != IntPtr.Zero)
        {
            return Marshal.PtrToStringAnsi(objNamePtr);
        }

        return string.Empty;
    }
}

public T GetVirtualFunction<T>(Offsets.VirtualFunctions function) where T : class
{
    return Magic.Instance.RegisterDelegate<T>(Magic.Instance.GetObjectVtableFunction(BaseAddress, (uint)function));
}

[FenixTX2]

Thanks for that MaiN,

I had a go at implemeting the template class, although I had to switch a few things to make it fit.

(BaseAddress and function are both uints,
In my tests BaseAddress is the base address of the local player
and function is 51)

        public T GetVirtualFunction<T>(uint function) where T : class
        {
            return Magic.RegisterDelegate<T>(Magic.GetObjectVtableFunction((IntPtr)BaseAddress, function));
        }

This throws an exception of "ArgumentNullException was unhandled 'Value cannot be null.
Parameter name: value'"

Within the code, it is actually

        (Magic.GetObjectVtableFunction((IntPtr)BaseAddress, function)

that is throwing the above exception.

*note, if i force to program to move passed that exception I still get the 'AccesViolationException' exception from 'IntPtr objNamePtr = GetObjectNameHandler(BaseAddress);'

[MaiN]

Thanks for that MaiN,

I had a go at implemeting the template class, although I had to switch a few things to make it fit.

(BaseAddress and function are both uints,
In my tests BaseAddress is the base address of the local player
and function is 51)

        public T GetVirtualFunction<T>(uint function) where T : class
        {
            return Magic.RegisterDelegate<T>(Magic.GetObjectVtableFunction((IntPtr)BaseAddress, function));
        }

This throws an exception of "ArgumentNullException was unhandled 'Value cannot be null.
Parameter name: value'"

Within the code, it is actually

        (Magic.GetObjectVtableFunction((IntPtr)BaseAddress, function)

that is throwing the above exception.

*note, if i force to program to move passed that exception I still get the 'AccesViolationException' exception from 'IntPtr objNamePtr = GetObjectNameHandler(BaseAddress);'

return Magic.RegisterDelegate<T>(Magic.Read<IntPtr>(BaseAddress, function * 4));

[FenixTX2]

Thanks again MaiN,

Sad to say that it's still not functioning.
I've done some digging and the error seems to stem from
ReadInternals within the Magic class.

Within that function there is a Byte[] called ba.
This is initialised wtih as

        Byte[] ba = _win32.ReadBytes(address, size);

However ba always turns out to be null.

The actual error comes from further into the ReadInternal function @

        case TypeCode.UInt32:
                    ret = BitConverter.ToUInt32(ba, 0);
                    break;

where ba is the null value in question.

Any ideas as to why this may be happening?

[Apoc]

Thanks again MaiN,

Sad to say that it's still not functioning.
I've done some digging and the error seems to stem from
ReadInternals within the Magic class.

Within that function there is a Byte[] called ba.
This is initialised wtih as

        Byte[] ba = _win32.ReadBytes(address, size);

However ba always turns out to be null.

The actual error comes from further into the ReadInternal function @

        case TypeCode.UInt32:
                    ret = BitConverter.ToUInt32(ba, 0);
                    break;

where ba is the null value in question.

Any ideas as to why this may be happening?

ba will only be null when Win32.ReadBytes fails. I suggest you do some actual debugging and figure out why ReadProcessMemory fails for you.

[Nesox]

@FenixTX2: do you have a CLR bootstrapper? and are injecting and running your managed assembly in / from wow? WhiteMagic is not mean't to work 'out of process'