Re: fs/exec.c and binfmt-xxx in 2.4.14

Heinz-Ado Arnolds (Ado.Arnolds@dhm-systems.de)
Thu, 22 Nov 2001 12:47:07 +0100

Andreas Ferber wrote:
>
> On Wed, Nov 21, 2001 at 05:58:26PM +0100, Heinz-Ado Arnolds wrote:
> >
> > When i now try to start an older binary in a.out format, which has a
> > magic number of 0x010b0064, it is translated with the 'new' code to a
> > request for "binfmt-0064" instead of "binfmt-267" as expected and
> > properly handled by modprobe.
>
> Then add
>
> alias binfmt-0064 binfmt_aout
>
> to /etc/modules.conf. Simple, isn't it?

That's a nice idea but I wouldn't rely on the fact that the third
and the fourth byte of a file are sufficient to identify the type.
If you look at the magic numbers in /etc/magic, you'll find:

0x00640107 Linux/i386 impure executable (OMAGIC)
0x00640108 Linux/i386 pure executable (NMAGIC)
0x0064010b Linux/i386 demand-paged executable (ZMAGIC)
0x006400cc Linux/i386 demand-paged executable (QMAGIC)
=0514 80386 COFF executable

It's standard to count on the first (and eventually following) bytes.

And if you look further on in /etc/magic, you'll see that there are
other file types having 0x0064 as 3rd and 4th byte.

I think it would not be a great deal to revert the changes in fs/exec.c

Thanks for your attention

Ado

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  Heinz-Ado Arnolds                        Ado.Arnolds@web-systems.net
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