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> Windows > 64 bit not understood sub rsp,8 !Goto page 1, 2, 3, 4, 5, 6, 7, 8, 9 Next |
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revolution 13 Dec 2020, 13:33
Unaligned stack.
Stack must be aligned to 16 else it is likely to crash when you call the OS API. |
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13 Dec 2020, 13:33 |
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Furs 13 Dec 2020, 15:31
revolution wrote: Unaligned stack.  |
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13 Dec 2020, 15:31 |
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Roman 21 Dec 2020, 14:18
64 bit its pain.
this crash. Ye. Stack not aligned. But somtime hard in code check stack align. Code: Start: sub rsp,8 mov rax,SomeTextInfo push rax invoke MessageBox,0,'some text',"Msg:",0 pop rax This is simple example. But happens more difficult code. I mean many pushs some registers. |
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21 Dec 2020, 14:18 |
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revolution 21 Dec 2020, 14:31
You didn't show all the code so we don't know what you have done.
But if we assume that "Start" is the first instruction then you definitely have an unaligned stack. Code: Start: sub rsp, 8 ;stack is now aligned push rax ;stack is now unaligned invoke ... ; BOOM! Code: ;... Start ; is this really the first instruction? the normal fasm header does a sub rsp, 8 so make sure push rbp ;stack is now aligned sub rsp, 0x20 ; allocate the shadow space, stack is still aligned invoke ... add rsp, 0x20 ;... |
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21 Dec 2020, 14:31 |
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Roman 21 Dec 2020, 14:48
Code:
proc ProcA
ret
endp
Start:
sub rsp,8
... BOOM ! some 230 line code
mov rax,SomeTextInfo
push rax
Call ProcA ;this work fine
pop rax
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21 Dec 2020, 14:48 |
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revolution 21 Dec 2020, 14:51
Still not complete code. We can't see how you get to Start.
Post a minimal version that we can compile showing the problem. Don't post 230 lines of unnecessary code. |
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21 Dec 2020, 14:51 |
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Roman 21 Dec 2020, 15:36
No problem.
I just understood what problems with the stack could be. And need very caution watch the stack align. Second moment. Invoke always do automatic sub and add rsp. Some time this not handful. Code: Start: sub rsp,8 mov rax,SomeTextInfo push rax invoke MessageBox,0,'some text',"Msg:",0 ;crash pop rax No crash: Start: sub rsp,8 mov rax,SomeTextInfo push rax sub rsp,8 xor rcx,rcx mov rdx,text xor r8,r8 xor r9,r9 Call [MessageBox] add rsp,8 pop rax Last edited by Roman on 22 Dec 2020, 07:20; edited 1 time in total |
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21 Dec 2020, 15:36 |
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Roman 21 Dec 2020, 15:54
My opineon good do mov [tmpBuf],rax
and not do push rax Profit one less pop rax and less problem with stack: invoke MessageBox,0,qword [tmpBuf],"Msg:",0 |
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21 Dec 2020, 15:54 |
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revolution 21 Dec 2020, 22:43
Roman: If you want help into your problem then post code that we can compile.
We don't know what you have done. We don't know what is in your invoke macro. We don't know how you get to Start. etc. Here is what I see when I compile the most recent code fragment you posted. Code: flat assembler version 1.73.08 (4052884 kilobytes memory) Roman.asm [2]: sub rsp,8 processed: sub rsp,8 error: illegal instruction. |
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21 Dec 2020, 22:43 |
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Roman 22 Dec 2020, 06:02
Quote: processed: sub rsp,8 What is mean? |
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22 Dec 2020, 06:02 |
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revolution 22 Dec 2020, 06:25
It means you haven't posted a working example of your problem.
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22 Dec 2020, 06:25 |
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Roman 22 Dec 2020, 07:23
Main proble MessageBox and maybe somthing els functions crash if rsp not aligned !
Code: ;This work fine proc vv ret endp proc vv2 push rbx ret pop rbx endp Code: push rax call vv ;This work fine pop rax push rdx call vv2 ;This work fine pop rdx Code: ;This crash. Remember in proc exist push rbp ! proc vv invoke MessageBoxA,0,"test",0,0 ;this crash place ret endp push rax call vv pop rax How I said its creates difficulties. And in some place code i do: push rax call vv pop rax I get crash and some time I will be surprised. Then search what is problem happens. |
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22 Dec 2020, 07:23 |
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revolution 22 Dec 2020, 07:43
Roman: That code doesn't compile.
We don't know what you have done. Post something we can compile. |
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22 Dec 2020, 07:43 |
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Roman 22 Dec 2020, 08:01
Compile this:
Code: format PE64 GUI 5.0 on 'nul' include 'include\win64a.inc' section '.code' code readable writeable executable proc vv invoke MessageBox,0,'Lets write code !','',0 ret endp Start: sub rsp,8 push rax ;this get crash. comment and get MessageBox call vv pop rax ;and comment this Code: ;This work fine format PE64 GUI 5.0 on 'nul' include 'include\win64a.inc' section '.code' code readable writeable executable proc vv mov edx,12 ret endp Start: sub rsp,8 push rax call vv pop rax Last edited by Roman on 22 Dec 2020, 08:08; edited 1 time in total |
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22 Dec 2020, 08:01 |
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revolution 22 Dec 2020, 08:06
Code: flat assembler version 1.73.08 (4031824 kilobytes memory) Roman.asm [5]: Msg 'f' processed: Msg 'f' error: illegal instruction. |
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22 Dec 2020, 08:06 |
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Roman 22 Dec 2020, 08:07
Code: macro Msg txt { invoke MessageBox,0,txt,'',0 } |
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22 Dec 2020, 08:07 |
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revolution 22 Dec 2020, 08:09
Please test before posting:
Code: flat assembler version 1.73.08 (4040884 kilobytes memory) Roman.asm [5]: invoke MessageBox,0,'Lets write code !','',0 .../macro/proc64.inc [5] invoke [0]: { common fastcall [proc],arg } .../macro/proc64.inc [300] fastcall [292]: call proc processed: call[MessageBox] error: undefined symbol 'MessageBox'. |
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22 Dec 2020, 08:09 |
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Roman 22 Dec 2020, 08:21
Use User32.dll and
import User32, MessageBox,'MessageBoxA' |
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22 Dec 2020, 08:21 |
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revolution 22 Dec 2020, 08:23
Show us how you do it. In the code. Post new fully complete code for us to compile.
We need to see how you get to Start, and exactly all the code. |
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22 Dec 2020, 08:23 |
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