multithread

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tthsqe

Joined: 20 May 2009
Posts: 767

tthsqe 12 Sep 2009, 23:47

Could someone post a simple exmple that demonstrates how to use multiple threads in a windows app?

12 Sep 2009, 23:47

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20516
Location: In your JS exploiting you and your system

revolution 13 Sep 2009, 03:36

Have a look at this post: http://board.flatassembler.net/topic.php?p=71735#71735

I just upload the simple thread tester again.

13 Sep 2009, 03:36

tthsqe

Joined: 20 May 2009
Posts: 767

tthsqe 14 Sep 2009, 04:24

If an argument is passed to a thread in CreateThread, how can the thread access this argument?

This is what I've got:

Code:

        sub     rsp,6*8
        mov     rcx,0
        mov     rdx,0
        lea     r8,[Thread]
        mov     r9,arg
        mov     qword [rsp+4*8],CREATE_SUSPENDED
        mov     qword [rsp+5*8],0
        call    [CreateThread]
        add     rsp,6*8 
...

Thread:
  where is arg?
....
        mov     rcx,0
        call    [ExitThread]

14 Sep 2009, 04:24

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20516
Location: In your JS exploiting you and your system

revolution 14 Sep 2009, 04:34

It is on that stack as the first parameter.

Win32 manual wrote:

DWORD WINAPI ThreadFunc( LPVOID lpParam )

14 Sep 2009, 04:34

tthsqe

Joined: 20 May 2009
Posts: 767

tthsqe 14 Sep 2009, 05:23

am I doing something wrong? it doesn't seem to be working

Code:

        mov     [var],7

        sub     rsp,6*8
        mov     rcx,0 
        mov     rdx,0 
        lea     r8,[Thread] 
        lea     r9,[var]
        mov     qword [rsp+4*8],CREATE_SUSPENDED 
        mov     qword [rsp+5*8],0 
        call    [CreateThread] 
        add     rsp,6*8  
... 

Thread: 
        mov     rax,[rsp]
        mov     rax,[rax]
        rax = 7 ?

14 Sep 2009, 05:23

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20516
Location: In your JS exploiting you and your system

revolution 14 Sep 2009, 05:36

Well since you seem to be using 64bit Windows then the first parameter is of course in a register (complying to the fastcall standard). IIRC it will be in rcx? Anyhow check the fastcall standard to confirm which register the first parameter is placed into.

BTW: For stdcall (with all parameters on the stack) the first parameter is [esp+4]. The return address is always at [esp] (and [rsp])

14 Sep 2009, 05:36

tthsqe

Joined: 20 May 2009
Posts: 767

tthsqe 14 Sep 2009, 06:10

great! I wouldn't have though it would be just like other function calls too. (I kept looking for it somewhere on the stack)

Quote:

IIRC it will be in rcx?

Yeah, arguments should be passed in

Code:

rcx, rdx, r8, r9, [rsp+8*4], [rsp+8*5],...

and r12-r15 should be preserved by the function.

14 Sep 2009, 06:10

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