linux-kernel - Re: [PATCH] Let CONFIG_STRICT_DEVMEM depends on CONFIG

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Message-ID: <20161007015957.GA9052@dhcp-128-65.nay.redhat.com>
Date:   Fri, 7 Oct 2016 09:59:57 +0800
From:   Dave Young <dyoung@...hat.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Paul McKenney <paulmck@...ux.vnet.ibm.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Tejun Heo <tj@...nel.org>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: Re: [PATCH] Let CONFIG_STRICT_DEVMEM depends on CONFIG_DEVMEM

On 10/06/16 at 02:39pm, Kees Cook wrote:
> On Wed, Oct 5, 2016 at 10:12 PM, Dave Young <dyoung@...hat.com> wrote:
> > With CONFIG_DEVMEM not set, CONFIG_STRICT_DEVMEM will be useless
> > even if it is set =y, thus let's update the dependency in Kconfig.
> >
> > Signed-off-by: Dave Young <dyoung@...hat.com>
> 
> Acked-by: Kees Cook <keescook@...omium.org>
> 
> > ---
> >  lib/Kconfig.debug |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > --- linux-x86.orig/lib/Kconfig.debug
> > +++ linux-x86/lib/Kconfig.debug
> > @@ -1980,7 +1980,7 @@ config ARCH_HAS_DEVMEM_IS_ALLOWED
> >
> >  config STRICT_DEVMEM
> >         bool "Filter access to /dev/mem"
> > -       depends on MMU
> > +       depends on MMU && DEVMEM
> >         depends on ARCH_HAS_DEVMEM_IS_ALLOWED
> >         default y if TILE || PPC
> >         ---help---
> 
> While we're at it, can we make DEVKMEM default=n? The help text even
> suggests making it "n".

It's fine to me, will send another patch for that.

Thanks
Dave

> 
> -Kees
> 
> -- 
> Kees Cook
> Nexus Security