linux-kernel - Re: /drivers/char/Kconfig Bug Kernel Patch

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Date:   Tue, 13 Dec 2016 16:05:09 -0800
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Max Bires <jbires@...gle.com>
Cc:     Arnd Bergmann <arnd@...db.de>, josh@...htriplett.org,
        linux-kernel@...r.kernel.org
Subject: Re: /drivers/char/Kconfig Bug Kernel Patch

On Tue, Dec 13, 2016 at 02:42:18PM -0800, Max Bires wrote:
> On Tue, Dec 13, 2016 at 1:37 PM, Arnd Bergmann <arnd@...db.de> wrote:
> >
> > On Tuesday, December 13, 2016 1:30:39 PM CET Max Bires wrote:
> > > While trying to turn off the port device in defconfig, I ran into a bug
> > > caused by the fact that the Kconfig for port didn't have a string after the
> > > bool declaration. I fixed this in the attached patch (though I figure the
> > > description might need tuning up). Let me know if there's anything else I
> > > need to do.
> >
> > The change looks reasonable, however there are a few things to improve
> > to get the patch applied:
> >
> > - clarify that the current behavior is not a bug, but was done intentionally.
> >   Making the option user-visible would help avoid a potential attack vector
> >   and make the kernel smaller, both of which are useful.
> >
> > - remove the "Change-id" line from the submission, it has no meaning in
> >   an upstream kernel
> >
> > - send the patch inline rather than as an attachment, this is usually done
> >   with git-send-email.
> >
> >         Arnd
> -First and second points have been addressed; I had some trouble with
> send-email, so let me know if the following isn't acceptable inlining.
> 
> >From c4a21c2ac0c587094000a3daeb13eec6056dc63f Mon Sep 17 00:00:00 2001
> From: Max <jbires@...gle.com>
> Date: Fri, 9 Dec 2016 15:16:47 -0800
> Subject: [PATCH] char: lack of bool string made CONFIG_DEVPORT always on
> 
> Without a bool string present, using "# CONFIG_DEVPORT is not set" in
> defconfig files would not actually unset devport. This ensured that
> /dev/port was always on, but there are reasons a user may wish to disable
> it (smaller kernel, attack surface reduction) if it's not being used. Adding
> a message here in order to make this user visible.

It's not ok, you don't see patches look like this on the mailing list,
right?  Please use git send-email to do this properly as a stand-alone
patch/email.

Also, your "From:" line doesn't match your signed-off-by line :(


> Signed-off-by: Max Bires <jbires@...gle.com>
> ---
>  drivers/char/Kconfig | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
> index 7ad3127..70e626c 100644
> --- a/drivers/char/Kconfig
> +++ b/drivers/char/Kconfig
> @@ -589,10 +589,13 @@ config TELCLOCK
>  	  controlling the behavior of this hardware.
> 
>  config DEVPORT
> -	bool
> +	bool "/dev/port character device"
>  	depends on !M68K
>  	depends on ISA || PCI
>  	default y
> +  help
> +    Say Y here if you want to support the /dev/port device. The

No tabs?

thanks,

greg k-h