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Message-ID: <81083a450512130632x59e86d35ka91ca5e37fecd7d7@mail.gmail.com>
Date: Tue, 13 Dec 2005 20:02:55 +0530
From: Ashutosh Naik <ashutosh.naik@gmail.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: [RFC][PATCH] Prevent overriding of Symbols in the Kernel, avoiding Undefined behaviour
Cc: Andrew Morton <akpm@osdl.org>, anandhkrishnan@yahoo.co.in,
       linux-kernel@vger.kernel.org, rusty@rustcorp.com.au, rth@redhat.com,
       greg@kroah.com, Jesper Juhl <jesper.juhl@gmail.com>,
       Arjan van de Ven <arjan@infradead.org>
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On 12/13/05, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:

> Its almost the 0% solution. The kernel as shipped doesn't seem to have
> any clashing symbols like this. The two sets of cases people report are
>
> 1. Out of tree modules
> 2. Reconfiguring, rebuilding something from kernel to module and not
> cleaning up
>
> A dep time solution might fix one of those but robustness here would be
> good, especially as once the installation is incorrect end users can
> often trigger hotplug loads that cause problems.

I agree with this.

I also would like to add that, the exported symbol may not always be
in the same module. Imagine if Module A is loaded and Module B would
export one symbol with the same symbol name as a symbol in Module A,
then the symbol exported by Module B would still go through. Now
Imagine if that symbol does something like a kmem_cache_create of an
existing cache!!

I feel this is a security loophole and preventing duplicate *exported*
symbols in the kernel, might just solve it.

Regards
Ashutosh
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