linux-kernel - Re: [PATCH] proc: prevent a task from writing on its own /proc/*/mem

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Date:   Sun, 27 May 2018 07:41:34 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Salvatore Mesoraca <s.mesoraca16@...il.com>,
        Jann Horn <jannh@...gle.com>,
        Kernel Hardening <kernel-hardening@...ts.openwall.com>,
        LSM List <linux-security-module@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-mm <linux-mm@...ck.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexey Dobriyan <adobriyan@...il.com>,
        Akinobu Mita <akinobu.mita@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Arnd Bergmann <arnd@...db.de>,
        Davidlohr Bueso <dave@...olabs.net>
Subject: Re: [PATCH] proc: prevent a task from writing on its own /proc/*/mem

On Sat, May 26, 2018 at 6:33 PM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
> Thus commit f511c0b17b08 "Yes, people use FOLL_FORCE ;)"
>
> Side note, that very sam ecommit f511c0b17b08 is also the explanation for
> why the patch under discussion now seems broken.
>
> People really do use "write to /proc/self/mem" as a way to keep the
> mappings read-only, but have a way to change them when required.

Ah! Yes, that is the commit I was trying to find. Thanks!

-Kees

-- 
Kees Cook
Pixel Security