Subject: Re: Why does insmod _not_ check for symbol redefinition ??
From: Rusty Russell <rusty@rustcorp.com.au>
To: "Tomar, Nagendra" <nagendra_tomar@adaptec.com>
Cc: linux-kernel@vger.kernel.org
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Date: Thu, 01 Dec 2005 11:57:09 +1100
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On Fri, 2005-11-25 at 10:45 +0530, Nagendra Singh Tomar wrote:
> Did'nt get any response to this one, so sending it again.
> 
> Can any of the module subsystem authors tell, why they have decided to 
> allow loading a kernel module having an EXPORTed symbol with the same name 
> as an EXPORTed  symbol in kernel proper. The safest thing would be to 
> disallow  module loading in this case, giving a "Symbol redefinition" 
> error.
> 	Allowing the module load will lead to overriding kernel functions
> which will affect modules loaded in future, that reference those 
> functions. Overall, it can have bad effects of varying severity.

Sure.  It was due to minimalism.  If you override a symbol it's
undefined behavior.  It should be fairly simple to add a check that
noone overrides a symbol.  We didn't bother checking for it because it
wasn't clear that it was problematic.

Hope that clarifies,
Rusty.
-- 
A bad analogy is like a leaky screwdriver -- Richard Braakman

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