linux-kernel - Re: Change CONFIG_DEVKMEM default value to n

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Message-ID: <CAGXu5jLZ1Q_WKgYO1GRae_10XFnCcvtob7SfRt0WZo2K_kRA_g@mail.gmail.com>
Date:   Fri, 7 Oct 2016 10:02:24 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Dave Young <dyoung@...hat.com>, Arnd Bergmann <arnd@...db.de>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: Change CONFIG_DEVKMEM default value to n

On Thu, Oct 6, 2016 at 8:57 PM, Greg Kroah-Hartman
<gregkh@...uxfoundation.org> wrote:
> On Fri, Oct 07, 2016 at 10:04:11AM +0800, Dave Young wrote:
>> Kconfig comment suggests setting it as "n" if in doubt thus move the
>> default value to 'n'.
>>
>> Signed-off-by: Dave Young <dyoung@...hat.com>
>> Suggested-by: Kees Cook <keescook@...omium.org>
>> ---
>>  drivers/char/Kconfig |    2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> --- linux-x86.orig/drivers/char/Kconfig
>> +++ linux-x86/drivers/char/Kconfig
>> @@ -17,7 +17,7 @@ config DEVMEM
>>
>>  config DEVKMEM
>>       bool "/dev/kmem virtual device support"
>> -     default y
>> +     default n
>
> If you remove the "default" line, it defaults to 'n'.
>
> And is it really "safe" to default this to n now?

This is DEVKMEM which distros haven't (shouldn't have?) used for a
while now. I'm not so bold as to suggest making DEVMEM default-n yet.
;)

-Kees

-- 
Kees Cook
Nexus Security