linux-kernel - Re: patch: VFS: fix passing of AT_PHDR value in auxv to ELF interpreter

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Date:	Fri, 04 May 2007 21:24:05 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Quentin Godfroy <godfroy@...pper.ens.fr>
CC:	linux-kernel@...r.kernel.org,
	Alexander Viro <viro@...iv.linux.org.uk>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	"David A. Madore" <David.Madore@....fr>,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: patch: VFS: fix passing of AT_PHDR value in auxv to ELF interpreter

Quentin Godfroy wrote:
>> Won't this break with ET_DYN executables?  And besides, isn't this the
>> same thing?                                                           
>>     
>
> Indeed, I haven't seen that. For ET_DYN executables, it could be done a
> thing like load_addr+elf_ppnt->p_vaddr (in the function that creates the
> auxv, as ity has access to the elf header), and for ET_EXEC do what I
> propose. I think this is trivial to do. I'll do it as soon as I come back
> in front of my machine.
>   

I don't think you need to special-case it.  You can compute the offset
between the linked address and the load address (first
PT_LOAD[0]->p_vaddr - load_addr) and use that to offset all the other
addresses.


> I don't understand. Yes it is what it is supposed to be, and the kernel
> is supposed to give the vaddr of the phdr table to the interpreter and
> not load addr + offset of phdr in file, which is sometimes wrong.
>   

How can it be wrong?  Does the PT_PHDR point to a different array of
Phdr entries?

    J
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