Shoutbox

non of you understand this at all

in my first attempt in javascript...
ive allocated some memory for my function,.
Put each individual instruction into an array (in hex of course)
Used a for(i in Patch_Function) to help store each instruction into the allocated memory like so

code:

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var BuffAddr = FunctionBuffer.DataPtr;
for(var i = 0; i < Patch_Function.length; i++){
        Patch(BuffAddr, Patch_Function[i]);
        BuffAddr += Patch_Function[i].length;
    }

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this works fine and well but now i have to create a JMP to this FunctionBuffer.DataPtr so it can execute my code and IT CANNOT BE HARD CODED which you have all obviously got wrong even though you have read it is dynamically allocated!

to create the jump ive done this

code:

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Hook_JMP = Interop.Allocate(6);
    var tmp = Interop.Allocate(6);
    tmp.WriteDWORD(1, FunctionBuffer.DataPtr-Hook_Address-5);
   
    var tmpbyte = tmp.GetAt(0);
    Hook_JMP.SetAt(5,tmpbyte);
   
    tmpbyte = tmp.GetAt(1);
    Hook_JMP.SetAt(4,tmpbyte);
   
    tmpbyte = tmp.GetAt(2);
    Hook_JMP.SetAt(3,tmpbyte);
   
    tmpbyte = tmp.GetAt(3);
    Hook_JMP.SetAt(2,tmpbyte);
   
    tmpbyte = tmp.GetAt(4);
    Hook_JMP.SetAt(0,tmpbyte);
   
    Hook_JMP.SetAt(0,0xE9);

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I think the bytes have to be reversed thats why ive put the in a temp buffer then read it backwards but i am unsure.

OBVIOUSLY since its dynamic memory i can just use "asm (jmp $0xE900000000)"

Oh no, I understood what you meant. I just thought you said you had the function there. If the location of the function is variable, then you will need to jump to the first instruction to be executed, for example, asm(jmp pointer_to_my_function).

Now, the thing that I am NOT understanding is how you're executing this. I was assuming that you've got a compiled program and you want to call your function from it at some point. This would mean you need to replace some instructions in the original program. How are you editing the program in Javascript? Have you got it also in a data array?

Because, in that case, this is what you could do, which is what I was saying. At some point, your function will be allocated into memory. And at that point, you can get it's location. The method will be different for different methods of allocation. It seems that you've got this function in memory from javascript, and you've got access to that data from +. Is this right so far?

Okay  I can access the location of the allocated function ( using interop.alloc) i have viewed it will Ollydbg and it is definitely copied there correctly. The way i am calling it is as you say replacing a current opp with a JMP to the allocated function. The problem comes in creating the JMP code. If you could possibly give me some help in creating this as my attempts so far have failed, even if its C or C++ code i dont mind as i can easily implement this into a dll that i can call with the interop object

I'm not quite sure if using the Interop.Allocate function is safe enough for this though. Maybe you're better of using the memory allocation APIs from windows directly. In that way you know exactly where you're doing what. And you can perfectly control the scope and lifetime of the allocated memory.


EDIT:

quote:

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Originally posted by effection
non of you understand this at all

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Sorry for saying this and certainly no offense, but I think we all understood your very good. And seeing what you finaly did in that other thread, it confirms what we were saying all this time though....

Dynamic linking is not something I've done by hand before, but I don't think it will be much fun. Still, there's bound to be a dll interface definition on the internet somewhere.

ive got it all sorted thanks to some help from deAd

Nice! What did you end up doing?

I just did what i was always doing but there was something originally wrong with my Call creation code which i never could work out but it fixed itself eventually