Subject: BUG in 'ld': a proof
From: [email-masked] (root)

16 Jul 1997 13:18:18 -0700
Approved: [email-masked]
Distribution: cygnus
Message-ID: <[email-masked]>
Content-Type: text
Original-To: [email-masked]
Original-Cc: [email-masked]
In-Reply-To: <[email-masked]> from "[email-masked]" at Jul 15, 97 01:21:56 pm
Original-Sender: [email-masked]

Recently, a user of 'res2coff' sent me a program that would not load under
windows NT. He thought that the bug was the fault of 'res2coff'.

I have repeatedly reported this bug in this list, but I have never tried to
make the executable WORK by mdofiying it with my binary editor. I did that,
and the executable now loads without problems, confirming the theory I have
about this bug:

This happens because 'ld' gets confused with the addresses of each section,
and leaves GAPS between the sections, in the image layout. Those GAPS make
that NT's loader refuses to load the executable.

Here is the original section layout as reported with 'pedump' a binary dump
utility that comes with the 'lcc' package.

Section Table
  01 .text     VirtSize: 00106304  VirtAddr:  00004096 0x00001000
    raw data offs: 01024 raw data size: 106496

  02 .bss      VirtSize: 00005308  VirtAddr:  00110592 0x0001b000
    raw data offs: 00000 raw data size: 00000

  03 .data     VirtSize: 00015352  VirtAddr:  00118784 0x0001d000 (1b000+2pages)
    raw data offs: 107520 raw data size: 15360

  04 .idata    VirtSize: 00003180  VirtAddr:  00135168 0x00021000 (1d000+4pages)
    raw data offs: 122880 raw data size: 03584

  05 .stab     VirtSize: 00000960  VirtAddr:  00147456 0x00024000  <<< gap!!!
    raw data offs: 126464 raw data size: 01024                     this should
    relocation offs: 00000000  relocations:   00000000             be 23000!!!

  06 .stabstr  VirtSize: 00003093  VirtAddr:  00151552 0x00025000  and the error
    raw data offs: 127488 raw data size: 03584                     propagates
                                                                   to the other
  07 .rsrc     VirtSize: 00005594  VirtAddr:  00139264 0x00022000  sections after
    raw data offs: 131072 raw data size: 05632                     the wrong one

You can see that between the idata and the next section, the stab section,
there is a gap of 16K, but the idata section makes only for 3584 bytes,
i.e. only one page (4096) bytes.

To test this hypothesis I changed the positions of all sections to
make them consecutive using lcc's binary editor. I moved
The stab section to 139264 (0x22000)
The stabstr section to 143360 (0x23000)
The rsrc section to 147456 (0x24000)

and now your executable runs. I can't go on testing it since I do not have 
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
cygwin.dll

This is a bug in the linker, 'ld'.

-- 
Jacob Navia	Logiciels/Informatique
41 rue Maurice Ravel			Tel 01 48.23.51.44
93430 Villetaneuse 			Fax 01 48.23.95.39
France
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