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Re: ELF header kernel module wrong?

To: Keith Owens <kaos@melbourne.sgi.com>
Subject: Re: ELF header kernel module wrong?
From: michaels@jungo.com
Date: Mon, 26 Feb 2001 13:17:42 +0200
Cc: Tom Appermont <tea@sonycom.com>, linux-mips@oss.sgi.com
Organization: Jungo LTD
References: <11701.983148650@kao2.melbourne.sgi.com>
Sender: owner-linux-mips@oss.sgi.com
Keith,

If what you say is correct, then any module created by this toolchain
would be impossible to 'insmod', and that is not the case. As I said, we
have one module which we managed to install, and it was compiled with
exactly the same toolchain. The module is quite large, has a lot of
symbols, and was NOT taken from the kernel tree. I would suspect that
there is some problem with kernel module linkage that is incompatible
with mips toolchain. 

Besides that, in "old" modultils there IS a check for symtab size, and
it did work as expected. So, what you say is only part of the truth.

Keith Owens wrote:
> 
> On Sun, 25 Feb 2001 11:06:29 +0200,
> michaels@jungo.com wrote:
> >I have seen this problem too. My kernel is 2.2.14 though, using modutils
> >2.3.x.
> >I tried to do many things with modutils, tried even not to check the
> >boundary, but that caused crashes. The only solution that worked for me
> >was to step downwards to modutils 2.2.2. Even then, depmod segfaults
> >unless you put a remark on obj_free in some place... Hope you get a
> >better solution.
> 
> All you are doing by using old modutils is hiding the problem and
> risking storage corruption.  modutils follows the ELF specification
> 
>   "A symbol table section's sh_info section header member holds the
>   symbol table index for the first non-local symbol."
> 
> The mips toolchain is generating local symbols with index numbers
> greater than sh_info.  Old modutils did not check for that and silently
> created corrupt modules.  New modutils check this field for
> correctness.  Fix the mips toolchain.

-- 
Sincerely yours,
Michael Shmulevich
______________________________________
Software Developer
Jungo - R&D 
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