Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1496967 > unrolled thread

Change CONFIG_DEVKMEM default value to n

Started byDave Young <dyoung@redhat.com>
First post2016-10-07 04:10 +0200
Last post2016-10-10 07:40 +0200
Articles 7 — 3 participants

Back to article view | Back to linux.kernel

Contents

  Change CONFIG_DEVKMEM default value to n Dave Young <dyoung@redhat.com> - 2016-10-07 04:10 +0200
    Re: Change CONFIG_DEVKMEM default value to n Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-07 06:10 +0200
      Re: Change CONFIG_DEVKMEM default value to n Kees Cook <keescook@chromium.org> - 2016-10-07 19:10 +0200
      Re: Change CONFIG_DEVKMEM default value to n Dave Young <dyoung@redhat.com> - 2016-10-10 04:50 +0200
        Re: Change CONFIG_DEVKMEM default value to n Dave Young <dyoung@redhat.com> - 2016-10-10 05:00 +0200
          Re: Change CONFIG_DEVKMEM default value to n Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2016-10-10 07:20 +0200
            Re: Change CONFIG_DEVKMEM default value to n Dave Young <dyoung@redhat.com> - 2016-10-10 07:40 +0200

#1496967 — Change CONFIG_DEVKMEM default value to n

FromDave Young <dyoung@redhat.com>
Date2016-10-07 04:10 +0200
SubjectChange CONFIG_DEVKMEM default value to n
Message-ID<spsLM-1l4-5@gated-at.bofh.it>
Kconfig comment suggests setting it as "n" if in doubt thus move the
default value to 'n'.

Signed-off-by: Dave Young <dyoung@redhat.com>
Suggested-by: Kees Cook <keescook@chromium.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
 	help
 	  Say Y here if you want to support the /dev/kmem device. The
 	  /dev/kmem device is rarely used, but can be used for certain

[toc] | [next] | [standalone]

#1496984

FromGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Date2016-10-07 06:10 +0200
Message-ID<spuDU-2QL-17@gated-at.bofh.it>
In reply to#1496967
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@redhat.com>
> Suggested-by: Kees Cook <keescook@chromium.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?

thanks,

greg k-h

[toc] | [prev] | [next] | [standalone]

#1497363

FromKees Cook <keescook@chromium.org>
Date2016-10-07 19:10 +0200
Message-ID<spGOJ-3x4-11@gated-at.bofh.it>
In reply to#1496984
On Thu, Oct 6, 2016 at 8:57 PM, Greg Kroah-Hartman
<gregkh@linuxfoundation.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@redhat.com>
>> Suggested-by: Kees Cook <keescook@chromium.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

[toc] | [prev] | [next] | [standalone]

#1498068

FromDave Young <dyoung@redhat.com>
Date2016-10-10 04:50 +0200
Message-ID<sqyP7-3YV-5@gated-at.bofh.it>
In reply to#1496984
On 10/07/16 at 05:57am, Greg Kroah-Hartman 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@redhat.com>
> > Suggested-by: Kees Cook <keescook@chromium.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'.

I personally perfer a "default n", but I can update it..

> 
> And is it really "safe" to default this to n now?

There is an old article here:
https://lwn.net/Articles/147901/

AFAIK Distributions like Fedora/Debian has disabled it for long time.
If one really need it he can still enable it in his own config file.

> 
> thanks,
> 
> greg k-h

Thanks
Dave

[toc] | [prev] | [next] | [standalone]

#1498069

FromDave Young <dyoung@redhat.com>
Date2016-10-10 05:00 +0200
Message-ID<sqyYO-41U-3@gated-at.bofh.it>
In reply to#1498068
On 10/10/16 at 10:44am, Dave Young wrote:
> On 10/07/16 at 05:57am, Greg Kroah-Hartman 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@redhat.com>
> > > Suggested-by: Kees Cook <keescook@chromium.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'.
> 
> I personally perfer a "default n", but I can update it..

Greg, here is an update with dropping the default line:

Move CONFIG_DEVKMEM default to n

Kconfig comment suggests setting it as "n" if in doubt thus move the
default value to 'n'.

Signed-off-by: Dave Young <dyoung@redhat.com>
Suggested-by: Kees Cook <keescook@chromium.org>
---
 drivers/char/Kconfig |    1 -
 1 file changed, 1 deletion(-)

--- linux-x86.orig/drivers/char/Kconfig
+++ linux-x86/drivers/char/Kconfig
@@ -17,7 +17,6 @@ config DEVMEM
 
 config DEVKMEM
 	bool "/dev/kmem virtual device support"
-	default y
 	help
 	  Say Y here if you want to support the /dev/kmem device. The
 	  /dev/kmem device is rarely used, but can be used for certain

[toc] | [prev] | [next] | [standalone]

#1498102

FromGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Date2016-10-10 07:20 +0200
Message-ID<sqBah-5zI-7@gated-at.bofh.it>
In reply to#1498069
On Mon, Oct 10, 2016 at 10:50:50AM +0800, Dave Young wrote:
> On 10/10/16 at 10:44am, Dave Young wrote:
> > On 10/07/16 at 05:57am, Greg Kroah-Hartman 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@redhat.com>
> > > > Suggested-by: Kees Cook <keescook@chromium.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'.
> > 
> > I personally perfer a "default n", but I can update it..
> 
> Greg, here is an update with dropping the default line:

<snip>

Can you resend it in a format I can apply it in?

thanks,

greg k-h

[toc] | [prev] | [next] | [standalone]

#1498103

FromDave Young <dyoung@redhat.com>
Date2016-10-10 07:40 +0200
Message-ID<sqBtD-5FM-1@gated-at.bofh.it>
In reply to#1498102
On 10/10/16 at 07:12am, Greg Kroah-Hartman wrote:
> On Mon, Oct 10, 2016 at 10:50:50AM +0800, Dave Young wrote:
> > On 10/10/16 at 10:44am, Dave Young wrote:
> > > On 10/07/16 at 05:57am, Greg Kroah-Hartman 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@redhat.com>
> > > > > Suggested-by: Kees Cook <keescook@chromium.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'.
> > > 
> > > I personally perfer a "default n", but I can update it..
> > 
> > Greg, here is an update with dropping the default line:
> 
> <snip>
> 
> Can you resend it in a format I can apply it in?

Done, thanks you!

> 
> thanks,
> 
> greg k-h

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web