Date: Tue, 15 Jan 2013 11:07:45 +0100
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: rebase segfault
Message-ID: <20130115100745.GC2353@calimero.vinschen.de>
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On Jan 15 09:43, marco atzeri wrote:
> rebase is segfaulting on two dlls of new package
> 
> postgresql-contrib-9.2.2-1
> 
> Full packages here
> http://matzeri.altervista.org/cygwin-1.7/postgresql/
> 
> Just the two dll's here:
> http://matzeri.altervista.org/works/rebase/
> 
> for i in *.dll; do echo $i ; rebase -O  $i ; done
> 
> dict_snowball.dll
> Segmentation fault (core dumped)
> 
> ltree.dll
> Segmentation fault (core dumped)

I don't know exactly what's going on here, but there's a common
factor:

$ objdump -h dict_snowball.dll

dict_snowball.dll:     file format pei-i386

Sections:
Idx Name          Size      VMA       LMA       File off  Algn
  0 .text         00016808  4ef01000  4ef01000  00000400  2**4
                  CONTENTS, ALLOC, LOAD, READONLY, CODE, DATA
  1 .data         00017180  4ef18000  4ef18000  00016e00  2**5
                  CONTENTS, ALLOC, LOAD, DATA
  2 .bss          000000f8  4ef30000  4ef30000  00000000  2**5
                  ALLOC
  3 .edata        00000fe0  4ef31000  4ef31000  0002e000  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  4 .idata        000003e0  4ef32000  4ef32000  0002f000  2**2
                  CONTENTS, ALLOC, LOAD, DATA
  5 .reloc        0000765c  4ef33000  4ef33000  0002f400  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  6 .gnu_deb      0000001c  4ef3b000  4ef3b000  00036c00  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA

$ objdump -h ltree.dll

ltree.dll:     file format pei-i386

Sections:
Idx Name          Size      VMA       LMA       File off  Algn
  0 .text         000088a8  4ef31000  4ef31000  00000400  2**4
                  CONTENTS, ALLOC, LOAD, READONLY, CODE, DATA
  1 .data         00000dc0  4ef3a000  4ef3a000  00008e00  2**5
                  CONTENTS, ALLOC, LOAD, DATA
  2 .bss          000000f8  4ef3b000  4ef3b000  00000000  2**5
                  ALLOC
  3 .edata        00000e3c  4ef3c000  4ef3c000  00009c00  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  4 .idata        000005b8  4ef3d000  4ef3d000  0000ac00  2**2
                  CONTENTS, ALLOC, LOAD, DATA
  5 .reloc        00000adc  4ef3e000  4ef3e000  0000b200  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  6 .gnu_deb      00000014  4ef3f000  4ef3f000  0000be00  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA

Both DLLs have a section .gnu_deb, whatever that one is good for.
Rebase crashes both times when trying to relocate this .gnu_deb section.
As you can see, the .gnu_deb section is pretty small, only 28 resp. 20
bytes.  What happens is that the relocation information for the .gnu_deb
section appears to be too big.  In case of dict_snowball.dll, the reloc
info covers 44 relocation entries.  The segfault occurs as soon as one
entry translates into a memory address which is beyond the committed
area of the file memory map.

Now, that's the *effect*.  From this I can't say what the *cause*
for this weird relocation info is.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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