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Date:   Sat, 02 Apr 2022 19:24:26 -0700
From:   Kees Cook <keescook@chromium.org>
To:     "Maciej W. Rozycki" <macro@orcam.me.uk>,
        James Jones <linux@theinnocuous.com>
CC:     bp@alien8.de, x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86: Remove a.out support
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On April 2, 2022 3:14:43 PM PDT, "Maciej W=2E Rozycki" <macro@orcam=2Eme=
=2Euk> wrote:
>On Wed, 16 Mar 2022, James Jones wrote:
>
>> Probably getting a bit off topic, but I did spend a few hours searching
>> around for any existing tools to convert a binary from a=2Eout->ELF, an=
d
>> trying to come up with something myself by extracting the sections with
>> objdump and re-combining them into an ELF using a linker script placing
>> the sections at the same locations=2E I couldn't get it working in an
>> evening or two messing with it so I moved on, but I agree something lik=
e
>> this seems possible in theory=2E
>
> Chiming in late as I'm scanning outstanding mailing list traffic: if thi=
s=20
>is as you say all statically linked stuff, then converting from a=2Eout t=
o=20
>ELF might be as easy as:
>
>$ objcopy -I a=2Eout-i386-linux -O elf32-i386 a=2Eout-binary elf-binary

Based on my research (and the wrapper I ended up writing), I don't think t=
his is sufficient because entry point handling is different between ELF and=
 a=2Eout (specifically the stack layout and initial sp register value)=2E

-Kees

--=20
Kees Cook