RE: rebase and ME

["Ralf Habacker" <Ralf dot Habacker at freenet dot de>]

> On Tue, Aug 06, 2002 at 04:04:13PM -0400, Jason Tishler wrote:
> > On Tue, Aug 06, 2002 at 08:58:28PM +0200, Ralf Habacker wrote:
> > > > Please try the appended patched rebase.
> > > >
> > > I haven't got any comments. Does this rebase not work ?
> >
> > Sorry, I've been backed up debugging an ipc-daemon problem.  I will try
> > your version under 2000 tomorrow morning.
>
> Actually, I just found some time.  Your version seems to rebase fine,
> but SEGVs on known problematic (stripped) DLLs:
>
>     $ cp /usr/bin/cygcurl-2.dll .
>     $ strip cygcurl-2.dll
>     $ ./rebase -l cygcurl-2.dll
>     cygcurl-2.dll ImageBase: 10000000 ImageSize: 00020000
>                                                  ^^^^^^^^
>     $ ./rebase -d -b 0x68000000 cygcurl-2.dll
>     Segmentation fault (core dumped)
>
> Note that stripping cygcurl-2.dll seems to whack the ImageSize.
>
> Without stripping we get the following:
>
>     $ cp /usr/bin/cygcurl-2.dll .
>     $ ./rebase -l cygcurl-2.dll
>     cygcurl-2.dll ImageBase: 10000000 ImageSize: 00069000
>     $ ../rebase/rebase -d -b 0x68000000 cygcurl-2.dll
>     $ ./rebase -l cygcurl-2.dll
>     cygcurl-2.dll ImageBase: 67f90000 ImageSize: 00069000
>
> Can you fix this problem?
>
The reason for this is, that the dll contains relocations, which are located in
sections, which are removed by stripping.

Unfortunally the relocations for this sections aren't removed, so rebase writes
to non existant locations.  See below


This are the sections of the stripped dll. See the VMA's

Sections:
Idx Name          Size      VMA       LMA       File off  Algn
  0 .text         00016000  10001000  10001000  00000400  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, CODE, DATA
  1 .data         00000400  10017000  10017000  00016400  2**2
                  CONTENTS, ALLOC, LOAD, DATA
  2 .bss          0000035c  10018000  10018000  00000000  2**2
                  ALLOC
  3 .edata        00000c00  10019000  10019000  00016800  2**2
                  CONTENTS, ALLOC, LOAD, DATA
  4 .idata        00001000  1001a000  1001a000  00017400  2**2
                  CONTENTS, ALLOC, LOAD, DATA
  5 .reloc        00001200  1001b000  1001b000  00018400  2**2
                  CONTENTS, ALLOC, LOAD, DATA

The relocations points to the relative virtual addresses (RVA), (substrate the
ImageBase (0x10000000) from the above VMA-entries th get the rva).

For example the first virtual adress 0x00001000 below mentioned points into the
.text segment. The second and ... too until (2) 0x00017000, which points into
the data segment.

Virtual Address: 00001000
Virtual Address: 00002000
<snip>
Virtual Address: 00015000
Virtual Address: 00016000
(2) Virtual Address: 00017000

And there is the problem:
If you look into the sections, you will not find a section with a rva of 0x1d000
and the relocation points into the nirvana. So it seems that "strip" contains a
bug.

Virtual Address: 0001d000
Virtual Address: 0001f000
<snip>
Virtual Address: 00044000

Can anyone tell me, which dll's are affected by this problem , so that I can
identify, what's going wrong with stripping ?

Ralf


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