linux-hardening - Re: [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 for Android: free password hash cracker in your pocket

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

Message-ID: <alpine.LNX.2.23.453.2011230938390.7@nippy.intranet>
Date:   Mon, 23 Nov 2020 09:54:48 +1100 (AEDT)
From:   Finn Thain <fthain@...egraphics.com.au>
To:     Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
cc:     James Bottomley <James.Bottomley@...senpartnership.com>,
        Kees Cook <keescook@...omium.org>,
        Jakub Kicinski <kuba@...nel.org>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        alsa-devel@...a-project.org, amd-gfx@...ts.freedesktop.org,
        bridge@...ts.linux-foundation.org, ceph-devel@...r.kernel.org,
        cluster-devel@...hat.com, coreteam@...filter.org,
        devel@...verdev.osuosl.org, dm-devel@...hat.com,
        drbd-dev@...ts.linbit.com, dri-devel@...ts.freedesktop.org,
        GR-everest-linux-l2@...vell.com, GR-Linux-NIC-Dev@...vell.com,
        intel-gfx@...ts.freedesktop.org, intel-wired-lan@...ts.osuosl.org,
        keyrings@...r.kernel.org, linux1394-devel@...ts.sourceforge.net,
        linux-acpi@...r.kernel.org, linux-afs@...ts.infradead.org,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-arm-msm@...r.kernel.org,
        linux-atm-general@...ts.sourceforge.net,
        linux-block@...r.kernel.org, linux-can@...r.kernel.org,
        linux-cifs@...r.kernel.org,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>,
        linux-decnet-user@...ts.sourceforge.net,
        Ext4 Developers List <linux-ext4@...r.kernel.org>,
        linux-fbdev@...r.kernel.org, linux-geode@...ts.infradead.org,
        linux-gpio@...r.kernel.org, linux-hams@...r.kernel.org,
        linux-hwmon@...r.kernel.org, linux-i3c@...ts.infradead.org,
        linux-ide@...r.kernel.org, linux-iio@...r.kernel.org,
        linux-input <linux-input@...r.kernel.org>,
        linux-integrity@...r.kernel.org,
        linux-mediatek@...ts.infradead.org,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        linux-mmc@...r.kernel.org, Linux-MM <linux-mm@...ck.org>,
        linux-mtd@...ts.infradead.org, linux-nfs@...r.kernel.org,
        linux-rdma@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        linux-scsi@...r.kernel.org, linux-sctp@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        linux-stm32@...md-mailman.stormreply.com,
        linux-usb@...r.kernel.org, linux-watchdog@...r.kernel.org,
        linux-wireless <linux-wireless@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        netfilter-devel@...r.kernel.org, nouveau@...ts.freedesktop.org,
        op-tee@...ts.trustedfirmware.org, oss-drivers@...ronome.com,
        patches@...nsource.cirrus.com, rds-devel@....oracle.com,
        reiserfs-devel@...r.kernel.org, samba-technical@...ts.samba.org,
        selinux@...r.kernel.org, target-devel@...r.kernel.org,
        tipc-discussion@...ts.sourceforge.net,
        usb-storage@...ts.one-eyed-alien.net,
        virtualization@...ts.linux-foundation.org,
        wcn36xx@...ts.infradead.org,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        xen-devel@...ts.xenproject.org, linux-hardening@...r.kernel.org,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Miguel Ojeda <ojeda@...nel.org>, Joe Perches <joe@...ches.com>
Subject: Re: [PATCH 000/141] Fix fall-through warnings for Clang


On Sun, 22 Nov 2020, Miguel Ojeda wrote:

> 
> It isn't that much effort, isn't it? Plus we need to take into account 
> the future mistakes that it might prevent, too.

We should also take into account optimisim about future improvements in 
tooling.

> So even if there were zero problems found so far, it is still a positive 
> change.
> 

It is if you want to spin it that way.

> I would agree if these changes were high risk, though; but they are 
> almost trivial.
> 

This is trivial:

 case 1:
	this();
+	fallthrough;
 case 2:
 	that();

But what we inevitably get is changes like this:

 case 3:
        this();
+       break;
 case 4:
        hmmm();

Why? Mainly to silence the compiler. Also because the patch author argued 
successfully that they had found a theoretical bug, often in mature code.

But is anyone keeping score of the regressions? If unreported bugs count, 
what about unreported regressions?

> Cheers,
> Miguel
>