From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933130AbaIDGqo (ORCPT ); Thu, 4 Sep 2014 02:46:44 -0400 Received: from mail-wi0-f170.google.com ([209.85.212.170]:45841 "EHLO mail-wi0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750803AbaIDGqm (ORCPT ); Thu, 4 Sep 2014 02:46:42 -0400 MIME-Version: 1.0 In-Reply-To: <20140904011420.GA31350@kroah.com> References: <1409784805-14190-1-git-send-email-fransklaver@gmail.com> <20140904004947.GA17138@vmdeb7> <20140904011420.GA31350@kroah.com> Date: Thu, 4 Sep 2014 08:46:40 +0200 Message-ID: Subject: Re: [PATCH] eeepc-laptop: remove possible use of uninitialized value From: Frans Klaver To: Greg Kroah-Hartman Cc: Darren Hart , Corentin Chary , Matthew Garrett , acpi4asus-user , platform-driver-x86 , 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 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. Thanks, Frans