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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id z68sm129381pgb.37.2020.11.24.13.25.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Nov 2020 13:25:41 -0800 (PST) Date: Tue, 24 Nov 2020 13:25:40 -0800 From: Kees Cook To: Nick Desaulniers Cc: Jakub Kicinski , "Gustavo A. R. Silva" , LKML , alsa-devel@alsa-project.org, amd-gfx list , bridge@lists.linux-foundation.org, ceph-devel@vger.kernel.org, cluster-devel@redhat.com, coreteam@netfilter.org, devel@driverdev.osuosl.org, dm-devel@redhat.com, drbd-dev@lists.linbit.com, dri-devel , GR-everest-linux-l2@marvell.com, GR-Linux-NIC-Dev@marvell.com, intel-gfx@lists.freedesktop.org, intel-wired-lan@lists.osuosl.org, keyrings@vger.kernel.org, linux1394-devel@lists.sourceforge.net, linux-acpi@vger.kernel.org, linux-afs@lists.infradead.org, Linux ARM , linux-arm-msm , linux-atm-general@lists.sourceforge.net, linux-block@vger.kernel.org, linux-can@vger.kernel.org, linux-cifs@vger.kernel.org, "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" , linux-decnet-user@lists.sourceforge.net, linux-ext4@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-geode@lists.infradead.org, linux-gpio@vger.kernel.org, linux-hams@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-i3c@lists.infradead.org, linux-ide@vger.kernel.org, linux-iio@vger.kernel.org, linux-input@vger.kernel.org, linux-integrity@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-media@vger.kernel.org, linux-mmc@vger.kernel.org, Linux Memory Management List , linux-mtd@lists.infradead.org, linux-nfs@vger.kernel.org, linux-rdma@vger.kernel.org, Linux-Renesas , linux-scsi@vger.kernel.org, linux-sctp@vger.kernel.org, linux-security-module@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-usb@vger.kernel.org, linux-watchdog@vger.kernel.org, linux-wireless , Network Development , netfilter-devel@vger.kernel.org, nouveau@lists.freedesktop.org, op-tee@lists.trustedfirmware.org, oss-drivers@netronome.com, patches@opensource.cirrus.com, rds-devel@oss.oracle.com, reiserfs-devel@vger.kernel.org, samba-technical@lists.samba.org, selinux@vger.kernel.org, target-devel@vger.kernel.org, tipc-discussion@lists.sourceforge.net, usb-storage@lists.one-eyed-alien.net, virtualization@lists.linux-foundation.org, wcn36xx@lists.infradead.org, "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" , xen-devel@lists.xenproject.org, linux-hardening@vger.kernel.org, Nathan Chancellor , Miguel Ojeda , Joe Perches Subject: Re: [PATCH 000/141] Fix fall-through warnings for Clang Message-ID: <202011241324.B3439A2@keescook> References: <20201120105344.4345c14e@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> <202011201129.B13FDB3C@keescook> <20201120115142.292999b2@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> <202011220816.8B6591A@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Nov 23, 2020 at 05:32:51PM -0800, Nick Desaulniers wrote: > On Sun, Nov 22, 2020 at 8:17 AM Kees Cook wrote: > > > > On Fri, Nov 20, 2020 at 11:51:42AM -0800, Jakub Kicinski wrote: > > > If none of the 140 patches here fix a real bug, and there is no change > > > to machine code then it sounds to me like a W=2 kind of a warning. > > > > FWIW, this series has found at least one bug so far: > > https://lore.kernel.org/lkml/CAFCwf11izHF=g1mGry1fE5kvFFFrxzhPSM6qKAO8gxSp=Kr_CQ@mail.gmail.com/ > > So looks like the bulk of these are: > switch (x) { > case 0: > ++x; > default: > break; > } > > I have a patch that fixes those up for clang: > https://reviews.llvm.org/D91895 I still think this isn't right -- it's a case statement that runs off the end without an explicit flow control determination. I think Clang is right to warn for these, and GCC should also warn. -- Kees Cook