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Date:      Thu, 02 Dec 1999 19:27:12 +0100
From:      Marcel Moolenaar <marcel@scc.nl>
To:        emulation@FreeBSD.org
Subject:   Re: Emulation kernel bug (linux)
Message-ID:  <3846BA00.C73BC6C6@scc.nl>
References:  <19991202172548.2955.qmail@abc.aaa-mainstreet.nl>

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gary@aaa-mainstreet.nl wrote:
> 
> A ktrace gives this:
> 
[snip]
>            792 ide      CALL  setreuid(0,0xbfbfdb50,0)
>            792 ide      RET   setreuid 0

Use linux_kdump to view the ktrace file or use truss.

>         main()
>         {
>                 setreuid(-1, -1);
>         }
> 
> Runs fine as a BSD binary.   I compile it under linux, though, and this happens:
> 
>         % ./lx
>         zsh: segmentation fault (core dumped)  ./lx

The Linux syscall is bodusly mapped onto the FreeBSD syscall. uid_t is
short in Linux and int in FreeBSD.

> Does it look familiar?  Looks like the Visual Age problem.  And I assume
> it is a bug, yes?

It is a bug, yes.

> So,  is this a known problem?

setreuid is, but trace you gave has nothing to do with resuid (the trace
shows 3 args, while sereuid only has 2).

> If not, can someone give me some help in solving this - I have starting
> playing around with .ko files, and want to write one to override the
> setreuid call for linux so that it does nothing.  I have just compiled
> my fist .ko file, and successfully loaded it (the helloworld example).

I wont stop you from writing your own module, but it's not the best way
to solve your problems :-)

> Any help much appreciated - and I'll gladly put in time to help improve the
> emulation - hey, you help me solve the kernel problems, and I'll make
> a port for the IBM program, OK?

Deal :-)

-- 
Marcel Moolenaar                        mailto:marcel@scc.nl
SCC Internetworking & Databases           http://www.scc.nl/
The FreeBSD project                mailto:marcel@FreeBSD.org


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