[Qemu-devel] [Bug 661696] Re: Ollydbg under Windows in qemu does not work as it does under native Windows.

[Paolo Bonzini]

linux-user testcase:

extern void *x;

int main()
{
        int a;
        asm volatile ("x: fldz\n\
             push %%edx\n\
             .byte 0xd9,0x74,0x24,0xf4\n\
             pop %%edx\n" : "=d" (a) : : "memory");
        printf ("%x %x\n", a, &x);
}

yakj:~ pbonzini$ ./a.out 
80483d9 80483d9
yakj:~ pbonzini$ qemu-i386 ./a.out 
0 80483d9


** Summary changed:

- Ollydbg under Windows in qemu does not work as it does under native Windows.
+ incomplete emulation of fstenv under TCG

-- 
incomplete emulation of fstenv under TCG
https://bugs.launchpad.net/bugs/661696
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Status in QEMU: New

Bug description:
Steps to reproduce:

1) Install Windows (tried XP and 7) in qemu (tried qemu without kvm and 
qemu-kvm).

2) Get OllyDbg ( http://ollydbg.de/odbg200.zip ).

3) Use some Metasploit-encoded file, example included.

It is not a virus!

File was generated with Metasploit, command (if i remember it right): 
`msfpayload windows/exec cmd=notepad R | msfencode -e x86/shikata_ga_nai -t exe 
-o cmd_exec_notepad.shikata_ga_nai.exe`.

4) Launch the file under Windows in qemu, make sure it opens a notepad.

5) Open file under OllyDbg, run (F9) it there. It opens a notpad. Close OllyDbg.

6) Open file under OllyDbg, trace over (Ctrl+F12) it there. It fails with 
`Access violation when writing to [some address]`.
Command: 316A 13, XOR DWORD PTR DS:[EDX+13],EBP 

Under native Windows, the trace over command works fine.

Under VMware the trace works fine.
Under VirtualBox it also fails (checked in the spring).

$ qemu-kvm --version
QEMU PC emulator version 0.12.5 (qemu-kvm-0.12.5), Copyright (c) 2003-2008 
Fabrice Bellard