FASM 1.63 Bug, MOVQ encoding

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r22

Joined: 27 Dec 2004
Posts: 805

r22 23 Jul 2005, 20:27

FASM:
section '.code' code readable executable
start:
movq qword[eax],xmm3
movq xmm4,qword[eax]

DECOMPILE:
.code:00402000 public start
.code:00402000 start proc near
.code:00402000 movq xmm3, xmm0
.code:00402004 movq qword ptr [eax], xmm4

Using XMMX registers with MOVQ seems to cause this bug.

23 Jul 2005, 20:27

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20421
Location: In your JS exploiting you and your system

revolution 24 Jul 2005, 01:13

Code:

use32
movq qword[eax],xmm3 ;66-0f-d6-18
movq xmm4,qword[eax] ;f3-0f-7e-20

Works correctly for me. What disassembler are you using?

24 Jul 2005, 01:13

r22

Joined: 27 Dec 2004
Posts: 805

r22 24 Jul 2005, 01:43

ida4.5 and ollydbg.
Odd I assume your using the newest release too revolution?

24 Jul 2005, 01:43

comrade

Joined: 16 Jun 2003
Posts: 1150
Location: Russian Federation

comrade 24 Jul 2005, 04:25

Tomasz sometimes puts a version out, and makes a quick fix to it without changing the version number. Try the downloading FASM again from the website.

24 Jul 2005, 04:25

comrade

Joined: 16 Jun 2003
Posts: 1150
Location: Russian Federation

comrade 24 Jul 2005, 04:26

The issue is present in an older version, 1.52, too though.

24 Jul 2005, 04:26

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20421
Location: In your JS exploiting you and your system

revolution 24 Jul 2005, 05:28

I think you need a new debugger/disassembler. FASM 1.63.1 does the correct job.

24 Jul 2005, 05:28

comrade

Joined: 16 Jun 2003
Posts: 1150
Location: Russian Federation

comrade 24 Jul 2005, 15:17

His debugger and disassembler are fine. He needs newer FASM vervsion

24 Jul 2005, 15:17

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20421
Location: In your JS exploiting you and your system

revolution 25 Jul 2005, 01:55

My Ollydbg v1.10d does not support SSE2/SSE3. Is there a later version already?

25 Jul 2005, 01:55

Reverend

Joined: 24 Aug 2004
Posts: 408
Location: Poland

Reverend 26 Jul 2005, 14:03

Afaik, v1.10d is the latest release from 1.x family. The next release will be v2.0

26 Jul 2005, 14:03

Mad_Overclocker

Joined: 11 Jan 2005
Posts: 20
Location: France,Earth

Mad_Overclocker 27 Jul 2005, 00:18

1.10 final is out :
http://www.ollydbg.de/odbg110.zip

27 Jul 2005, 00:18

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