linux-hardening - Re: [Intel-wired-lan] [PATCH 000/141] Fix fall-through warnings for Clang

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 25 Nov 2020 14:09:29 -0800
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Finn Thain <fthain@...egraphics.com.au>
Cc:     James Bottomley <James.Bottomley@...senpartnership.com>,
        Kees Cook <keescook@...omium.org>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Joe Perches <joe@...ches.com>,
        Jakub Kicinski <kuba@...nel.org>, alsa-devel@...a-project.org,
        linux-atm-general@...ts.sourceforge.net,
        reiserfs-devel@...r.kernel.org, linux-iio@...r.kernel.org,
        linux-wireless <linux-wireless@...r.kernel.org>,
        linux-fbdev@...r.kernel.org,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Nathan Chancellor <natechancellor@...il.com>,
        linux-ide@...r.kernel.org, dm-devel@...hat.com,
        keyrings@...r.kernel.org, linux-mtd@...ts.infradead.org,
        GR-everest-linux-l2@...vell.com, wcn36xx@...ts.infradead.org,
        samba-technical@...ts.samba.org, linux-i3c@...ts.infradead.org,
        linux1394-devel@...ts.sourceforge.net,
        linux-afs@...ts.infradead.org,
        usb-storage@...ts.one-eyed-alien.net, drbd-dev@...ts.linbit.com,
        devel@...verdev.osuosl.org, linux-cifs@...r.kernel.org,
        rds-devel@....oracle.com, linux-scsi@...r.kernel.org,
        linux-rdma@...r.kernel.org, oss-drivers@...ronome.com,
        bridge@...ts.linux-foundation.org,
        linux-security-module@...r.kernel.org,
        amd-gfx list <amd-gfx@...ts.freedesktop.org>,
        linux-stm32@...md-mailman.stormreply.com, cluster-devel@...hat.com,
        linux-acpi@...r.kernel.org, coreteam@...filter.org,
        intel-wired-lan@...ts.osuosl.org, linux-input@...r.kernel.org,
        Miguel Ojeda <ojeda@...nel.org>,
        tipc-discussion@...ts.sourceforge.net, linux-ext4@...r.kernel.org,
        linux-media@...r.kernel.org, linux-watchdog@...r.kernel.org,
        selinux@...r.kernel.org,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        intel-gfx@...ts.freedesktop.org, linux-geode@...ts.infradead.org,
        linux-can@...r.kernel.org, linux-block@...r.kernel.org,
        linux-gpio@...r.kernel.org, op-tee@...ts.trustedfirmware.org,
        linux-mediatek@...ts.infradead.org, xen-devel@...ts.xenproject.org,
        nouveau@...ts.freedesktop.org, linux-hams@...r.kernel.org,
        ceph-devel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-hwmon@...r.kernel.org,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        linux-nfs@...r.kernel.org, GR-Linux-NIC-Dev@...vell.com,
        Linux Memory Management List <linux-mm@...ck.org>,
        Network Development <netdev@...r.kernel.org>,
        linux-decnet-user@...ts.sourceforge.net, linux-mmc@...r.kernel.org,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        linux-sctp@...r.kernel.org, linux-usb@...r.kernel.org,
        netfilter-devel@...r.kernel.org,
        "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" 
        <linux-crypto@...r.kernel.org>, patches@...nsource.cirrus.com,
        linux-integrity@...r.kernel.org, target-devel@...r.kernel.org,
        linux-hardening@...r.kernel.org,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Greg KH <gregkh@...uxfoundation.org>
Subject: Re: [Intel-wired-lan] [PATCH 000/141] Fix fall-through warnings for Clang

On Wed, Nov 25, 2020 at 1:33 PM Finn Thain <fthain@...egraphics.com.au> wrote:
>
> Or do you think that a codebase can somehow satisfy multiple checkers and
> their divergent interpretations of the language spec?

Have we found any cases yet that are divergent? I don't think so.  It
sounds to me like GCC's cases it warns for is a subset of Clang's.
Having additional coverage with Clang then should ensure coverage for
both.

> > This is not a shiny new warning; it's already on for GCC and has existed
> > in both compilers for multiple releases.
> >
>
> Perhaps you're referring to the compiler feature that lead to the
> ill-fated, tree-wide /* fallthrough */ patch series.
>
> When the ink dries on the C23 language spec and the implementations figure
> out how to interpret it then sure, enforce the warning for new code -- the
> cost/benefit analysis is straight forward. However, the case for patching
> existing mature code is another story.

I don't think we need to wait for the ink to dry on the C23 language
spec to understand that implicit fallthrough is an obvious defect of
the C language.  While the kernel is a mature codebase, it's not
immune to bugs.  And its maturity has yet to slow its rapid pace of
development.
-- 
Thanks,
~Nick Desaulniers