Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752348AbcLMWuV (ORCPT ); Tue, 13 Dec 2016 17:50:21 -0500 Received: from mail-oi0-f54.google.com ([209.85.218.54]:34223 "EHLO mail-oi0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752068AbcLMWuU (ORCPT ); Tue, 13 Dec 2016 17:50:20 -0500 MIME-Version: 1.0 In-Reply-To: <25312310.aENfjP0Zdi@wuerfel> References: <25312310.aENfjP0Zdi@wuerfel> From: Max Bires Date: Tue, 13 Dec 2016 14:42:18 -0800 Message-ID: Subject: Re: /drivers/char/Kconfig Bug Kernel Patch To: Arnd Bergmann Cc: gregkh@linuxfoundation.org, josh@joshtriplett.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id uBDMoQBT016239 Content-Length: 2390 Lines: 63 On Tue, Dec 13, 2016 at 1:37 PM, Arnd Bergmann 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 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. Signed-off-by: Max Bires --- 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 + /dev/port device is similar to /dev/mem, but for I/O ports. config DCC_TTY tristate "DCC tty driver" -- 2.8.0.rc3.226.g39d4020