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

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Date:	Fri, 16 Nov 2012 10:00:35 -0800
From:	Kees Cook <keescook@...omium.org>
To:	P J P <ppandit@...hat.com>
Cc:	Al Viro <viro@...iv.linux.org.uk>, 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, Nov 16, 2012 at 4:50 AM, P J P <ppandit@...hat.com> wrote:
>
>   Hello folks,
>
> +-- On Mon, 12 Nov 2012, Kees Cook wrote --+
> | >   Al, what's your take on the *rare* extra call to request_module?
> |
> | Without any other feedback, I'd like to use my minimal allocation
> | patch, since it fixes the problem and doesn't change any of the
> | semantics of how/when loading happens.
>
>   I did apply and test this patch with kernel-3.5.3 on my machine. Now it
> seems to disclose dynamically allocated(kstrdup) bytes, instead of the call
> stack bytes. Recursions still dodge and exceed the limit of
> BINPRM_MAX_RECURSION(4).
>
> Please pardon my asking, but - how is this a fix?

Hrm? It should be showing only the live heap-allocated interp -- are
you seeing uninitialized contents?

-Kees

-- 
Kees Cook
Chrome OS Security
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