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Date:      Sun, 16 Nov 2003 22:13:23 +0200
From:      Murat Balaban <murat@enderunix.org>
To:        Kai Zhu <zkzklj@yahoo.com>
Cc:        freebsd-hackers@freebsd.org
Subject:   Re: Questions on intercepting execve syscall
Message-ID:  <20031116201323.GA26716@enderunix.org>
In-Reply-To: <20031116155330.42894.qmail@web21409.mail.yahoo.com>
References:  <20031116155330.42894.qmail@web21409.mail.yahoo.com>

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Hi, 
It might be that you have some bad address in the execve index of sysent array.
See http://www.enderunix.org/murat/linux_subexec/linux_subexec.c for a simple example.

PS: don't mind the naming :).

On Sun, Nov 16, 2003 at 07:53:30AM -0800, Kai Zhu wrote:
> Hello all,
>  
> I am writing a KLD module to intercept execve() as following:
>  
> static int my_execve(struct thread *td, struct execve_args *uap)
> {
>   return(execve(td,uap));
> }
>  
> As you can see, I first just want to make sure that my_execve won't affect the original execve, then I will add some new logic in my_execve before returning to execve().
> After kldload with this module, I always get "Bad address" error if I use any command like ls, cd, etc. 
>  
> Does anyone know where my problem is? Thanks!
> 
> 
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-- 
"When all else fails, read the instructions -- Murphy's Technology Laws"

Murat Balaban
http://www.enderunix.org



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