Re: Change CONFIG_DEVKMEM default value to n

[Dave Young]

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 
> > > > > Suggested-by: Kees Cook 
> > > > > ---
> > > > >  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:
> 
> 
> 
> Can you resend it in a format I can apply it in?

Done, thanks you!

> 
> thanks,
> 
> greg k-h

Re: Change CONFIG_DEVKMEM default value to n

[Dave Young]

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 
> > > > > Suggested-by: Kees Cook 
> > > > > ---
> > > > >  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:
> 
> 
> 
> Can you resend it in a format I can apply it in?

Done, thanks you!

> 
> thanks,
> 
> greg k-h

Re: Change CONFIG_DEVKMEM default value to n

[Greg Kroah-Hartman]

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 
> > > > Suggested-by: Kees Cook 
> > > > ---
> > > >  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:



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

thanks,

greg k-h

Re: Change CONFIG_DEVKMEM default value to n

[Greg Kroah-Hartman]

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 
> > > > Suggested-by: Kees Cook 
> > > > ---
> > > >  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:



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

thanks,

greg k-h

Re: Change CONFIG_DEVKMEM default value to n

[Dave Young]

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 
> > > Suggested-by: Kees Cook 
> > > ---
> > >  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 
Suggested-by: Kees Cook 
---
 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

Re: Change CONFIG_DEVKMEM default value to n

[Dave Young]

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 
> > > Suggested-by: Kees Cook 
> > > ---
> > >  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 
Suggested-by: Kees Cook 
---
 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

Re: Change CONFIG_DEVKMEM default value to n

[Dave Young]

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 
> > Suggested-by: Kees Cook 
> > ---
> >  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

Re: Change CONFIG_DEVKMEM default value to n

[Dave Young]

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 
> > Suggested-by: Kees Cook 
> > ---
> >  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

Re: Change CONFIG_DEVKMEM default value to n

[Kees Cook]

On Thu, Oct 6, 2016 at 8:57 PM, 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 
>> Suggested-by: Kees Cook 
>> ---
>>  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

Re: Change CONFIG_DEVKMEM default value to n

[Kees Cook]

On Thu, Oct 6, 2016 at 8:57 PM, 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 
>> Suggested-by: Kees Cook 
>> ---
>>  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

Re: Change CONFIG_DEVKMEM default value to n

[Greg Kroah-Hartman]

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 
> Suggested-by: Kees Cook 
> ---
>  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

Re: Change CONFIG_DEVKMEM default value to n

[Greg Kroah-Hartman]

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 
> Suggested-by: Kees Cook 
> ---
>  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

Change CONFIG_DEVKMEM default value to n

[Dave Young]

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

Signed-off-by: Dave Young 
Suggested-by: Kees Cook 
---
 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

Change CONFIG_DEVKMEM default value to n

[Dave Young]

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

Signed-off-by: Dave Young 
Suggested-by: Kees Cook 
---
 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