Relocations table in MZ files not supported

[VladRassokhin]

Subj. Have old dos mz executable with relocation table.
Beginning of file:

[0x00000000 752 Downloads/motor-city/IDMAS.EXE]> x
- offset -  0 1  2 3  4 5  6 7  8 9  A B  C D  E F  0123456789ABCDEF
0000:0000  4d5a 7000 3b01 2709 4c02 774a 774a 412b  MZp.;.'.L.wJwJA+
0000:0010  0034 0000 4800 0000 1c00 0000 4b00 0000  .4..H.......K...
0000:0020  5000 0000 5500 0000 6600 0000 8400 0000  P...U...f.......
0000:0030  9900 0000 a300 0000 af00 0000 c600 0000  ................
0000:0040  de00 0000 e300 0000 f400 0000 f900 0000  ................
0000:0050  2401 0000 4201 0000 5601 0000 6801 0000  $...B...V...h...

As you can see relocation talbe starts at 0000:001c and contains 0x13b elements.

Radare 2 not processed relocation table, and after start comes into

[0000:0048]> x 10
- offset -  0 1  2 3  4 5  6 7  8 9  A B  C D  E F  0123456789ABCDEF
0000:0048  f400 0000 f900 0000 2401                 ........$.

which is part of relocation table.

[VladRassokhin]

Is there any documentation about inner structures, e.g. RBinRelloc ?
I'm trying to implement method which would provide reallocs information for mz files, but does not understand what means all those fields of scructure RBinRelloc.
As example i'm looking into bin_pe.c, but no luck still.

[radare]

Relocs are not supported in any file format. They are only listed, but they do not virtually modify the io layer yet. That should be easy to do, but im currently busy in other todo points. Anyway, whats the output radiff2 -r IDMAS.exe?

Iirc there's a pad collecting all kind of random information about different relocation types on different file formats in order to define it properly to be crossplatform.

On 13 Aug 2014, at 17:14, Vladislav Rassokhin notifications@github.com wrote:

Subj. Have old dos mz executable with relocation table.
Beginning of file:

[0x00000000 752 Downloads/motor-city/IDMAS.EXE]> x

• offset - 0 1 2 3 4 5 6 7 8 9 A B C D E F 0123456789ABCDEF
  0000:0000 4d5a 7000 3b01 2709 4c02 774a 774a 412b MZp.;.'.L.wJwJA+
  0000:0010 0034 0000 4800 0000 1c00 0000 4b00 0000 .4..H.......K...
  0000:0020 5000 0000 5500 0000 6600 0000 8400 0000 P...U...f.......
  0000:0030 9900 0000 a300 0000 af00 0000 c600 0000 ................
  0000:0040 de00 0000 e300 0000 f400 0000 f900 0000 ................
  0000:0050 2401 0000 4201 0000 5601 0000 6801 0000 $...B...V...h...
  As you can see relocation talbe starts at 0000:001c and contains 0x13b elements.

Radare 2 not processed relocation table, and after start comes into

[0000:0048]> x 10

• offset - 0 1 2 3 4 5 6 7 8 9 A B C D E F 0123456789ABCDEF
  0000:0048 f400 0000 f900 0000 2401 ........$.
  which is part of relocation table.

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[radare]

Nope there's no documentation on that. Just check how it's used in pe, elf or mach0. This is implemented but not used so far the symbol definition (relocs does not yet modify io memory yet)

On 13 Aug 2014, at 17:57, Vladislav Rassokhin notifications@github.com wrote:

Is there any documentation about inner structures, e.g. RBinRelloc ?
I'm trying to implement method which would provide reallocs information for mz files, but does not understand what means all those fields of scructure RBinRelloc.
As example i'm looking into bin_pe.c, but no luck still.

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[VladRassokhin]

Ok, thanks for information.
radiff2 -r idmas.exe does not works, did you mean some other command?

[radare]

No, thats correct because as you said its not implemented for mz :) only for pe iirc

On 13 Aug 2014, at 18:30, Vladislav Rassokhin notifications@github.com wrote:

Ok, thanks for information.
'radiff2 -r idmas.exe' does not works, did you mean some other command?

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[radare]

can we have a test case for this?

[Maijin]

@marespiaut "can we have a test case for this?" ?

[ghost]

@Maijin It's not possible yet. First of all, because Motor City isn't a freeware game, so I have to find a freeware binary with the same problem. Second of all, I don't know (yet) what this is about, as I'm not familiar with the concept of relocation table.

[Maijin]

Well yeah no problem take something else ^^

[radare]

any other bin?

[ghost]

@radare Not for now. I'll do some research this evening.

[radare]

@marespiaut any update?

[VladRassokhin]

Good news, seems it was fixed in 0c57a43 or bit later.

[Maijin]

@marespiaut ^