linux-kernel - Re: [PATCH] exec: do not leave bprm->interp on stack

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Message-ID: <20121026183601.GR2616@ZenIV.linux.org.uk>
Date:	Fri, 26 Oct 2012 19:36:01 +0100
From:	Al Viro <viro@...IV.linux.org.uk>
To:	P J P <ppandit@...hat.com>
Cc:	Kees Cook <keescook@...omium.org>, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Josh Triplett <josh@...htriplett.org>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	linux-fsdevel@...r.kernel.org, halfdog <me@...fdog.net>
Subject: Re: [PATCH] exec: do not leave bprm->interp on stack

On Fri, Oct 26, 2012 at 11:08:20PM +0530, P J P wrote:
> +-- On Thu, 25 Oct 2012, Al Viro wrote --+
> | 	* every bleeding script will have bogus execution of modprobe done
> | at execve time (and you'd better pray that /sbin/modprobe isn't a shell
> | script wrapper around the actual binary, or you *will* get loop prevention
> | kick in)
> | 	* none of the existing binfmt-<...> aliases is going to be hit
> | now; IOW, all usecases got broken.  Granted, realistically it just means
> | broken modular aout support, but then it's the only reason to have that
> | request_module() there in the first place.
> 
>   Please have a look at the updated patch below.
> 
> It fixes the issue of excessive calls to request_module. find_module() routine 
> is used before request_module(), to see if the module is already loaded or 
> not. Module alias could dodge this though, I guess.

"Could"?  Can you show a single module that would have name matching
binfmt-[0-9a-f]*?  In other words, are they ever loaded _not_ via an
alias?
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