From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753111AbaIDOKo (ORCPT ); Thu, 4 Sep 2014 10:10:44 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:52669 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752331AbaIDOKm (ORCPT ); Thu, 4 Sep 2014 10:10:42 -0400 Date: Thu, 4 Sep 2014 07:10:41 -0700 From: Greg Kroah-Hartman To: Frans Klaver Cc: Darren Hart , Corentin Chary , Matthew Garrett , acpi4asus-user , platform-driver-x86 , linux-kernel@vger.kernel.org Subject: Re: [PATCH] eeepc-laptop: remove possible use of uninitialized value Message-ID: <20140904141041.GB23299@kroah.com> References: <1409784805-14190-1-git-send-email-fransklaver@gmail.com> <20140904004947.GA17138@vmdeb7> <20140904011420.GA31350@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 04, 2014 at 08:46:40AM +0200, Frans Klaver wrote: > On Thu, Sep 4, 2014 at 3:14 AM, Greg Kroah-Hartman > wrote: > > On Wed, Sep 03, 2014 at 05:49:47PM -0700, Darren Hart wrote: > >> On Thu, Sep 04, 2014 at 12:53:25AM +0200, Frans Klaver wrote: > >> > In store_sys_acpi, if count equals zero, or parse_arg()s sscanf call > >> > fails, 'value' remains possibly uninitialized. In that case 'value' > >> > shouldn't be used to produce the store_sys_acpi()s return value. > > Here I should probably remove either 'the' or the 's' after store_sys_acpi(). > > > >> > Only test the return value of set_acpi() if we can actually call it. > >> > Return rv otherwise. > >> > > >> > Signed-off-by: Frans Klaver > >> > --- > >> > drivers/platform/x86/eeepc-laptop.c | 8 ++++---- > >> > 1 file changed, 4 insertions(+), 4 deletions(-) > >> > > >> > diff --git a/drivers/platform/x86/eeepc-laptop.c b/drivers/platform/x86/eeepc-laptop.c > >> > index bd533c2..41f12ba 100644 > >> > --- a/drivers/platform/x86/eeepc-laptop.c > >> > +++ b/drivers/platform/x86/eeepc-laptop.c > >> > @@ -279,10 +279,10 @@ static ssize_t store_sys_acpi(struct device *dev, int cm, > >> > int rv, value; > >> > > >> > rv = parse_arg(buf, count, &value); > >> > - if (rv > 0) > >> > - value = set_acpi(eeepc, cm, value); > >> > >> That was rather horrible wasn't it? :-) > >> > >> > - if (value < 0) > >> > - return -EIO; > >> > + if (rv > 0) { > >> > + if (set_acpi(eeepc, cm, value) < 0) > >> > + return -EIO; > >> > >> Is there a compelling reason not to propogate the return code of set_acpi? > >> (ENODEV specifically). I see -EIO in Documentation/filesystems/sysfs.txt, but > >> it's used by default if the show() pointer is NULL (for example), but otherwise > >> propogates the error. > >> > >> Specifically it states: > >> > >> - show() or store() can always return errors. If a bad value comes > >> through, be sure to return an error. > >> > >> Greg, does this need to be -EIO? or is returning someting like ENODEV preferable > >> if it more accurately reflects the error? > > > > Just return the value of set_acpi() and you should be fine. > > According to 6dff29b63a5bf2eaf3313cb8a84f0b7520c43401 "eeepc-laptop: > disp attribute should be write-only" it should be -EIO. -ENODEV would > be misleading. If something is "write only" then there should not be a store function for it at all, the file should not be marked as writable, to prevent anything from ever being written to it at the higher-level filesystem layer, and never get down to the driver layer... thanks, greg k-h