netdev - Re: [PATCH 2/6] treewide: remove using list iterator after loop body as a ptr

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]

Message-ID: <202203011008.AA0B5A2D@keescook>
Date:   Tue, 1 Mar 2022 10:14:07 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Matthew Wilcox <willy@...radead.org>,
        Christian König <christian.koenig@....com>,
        Jakob Koschel <jakobkoschel@...il.com>,
        alsa-devel@...a-project.org, linux-aspeed@...ts.ozlabs.org,
        "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        linux-iio@...r.kernel.org, nouveau@...ts.freedesktop.org,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Cristiano Giuffrida <c.giuffrida@...nl>,
        amd-gfx list <amd-gfx@...ts.freedesktop.org>,
        samba-technical@...ts.samba.org,
        linux1394-devel@...ts.sourceforge.net, drbd-dev@...ts.linbit.com,
        linux-arch <linux-arch@...r.kernel.org>,
        CIFS <linux-cifs@...r.kernel.org>,
        KVM list <kvm@...r.kernel.org>,
        linux-scsi <linux-scsi@...r.kernel.org>,
        linux-rdma <linux-rdma@...r.kernel.org>,
        linux-staging@...ts.linux.dev, "Bos, H.J." <h.j.bos@...nl>,
        Jason Gunthorpe <jgg@...pe.ca>,
        intel-wired-lan@...ts.osuosl.org,
        kgdb-bugreport@...ts.sourceforge.net,
        bcm-kernel-feedback-list@...adcom.com,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        Arnd Bergman <arnd@...db.de>,
        Linux PM <linux-pm@...r.kernel.org>,
        intel-gfx <intel-gfx@...ts.freedesktop.org>,
        Brian Johannesmeyer <bjohannesmeyer@...il.com>,
        Nathan Chancellor <nathan@...nel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        v9fs-developer@...ts.sourceforge.net,
        linux-tegra <linux-tegra@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        linux-sgx@...r.kernel.org,
        linux-block <linux-block@...r.kernel.org>,
        Netdev <netdev@...r.kernel.org>, linux-usb@...r.kernel.org,
        linux-wireless <linux-wireless@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux F2FS Dev Mailing List 
        <linux-f2fs-devel@...ts.sourceforge.net>,
        tipc-discussion@...ts.sourceforge.net,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>,
        dma <dmaengine@...r.kernel.org>,
        linux-mediatek@...ts.infradead.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Mike Rapoport <rppt@...nel.org>
Subject: Re: [PATCH 2/6] treewide: remove using list iterator after loop body
 as a ptr

On Mon, Feb 28, 2022 at 04:45:11PM -0800, Linus Torvalds wrote:
> Really. The "-Wshadow doesn't work on the kernel" is not some new
> issue, because you have to do completely insane things to the source
> code to enable it.

The first big glitch with -Wshadow was with shadowed global variables.
GCC 4.8 fixed that, but it still yells about shadowed functions. What
_almost_ works is -Wshadow=local. At first glace, all the warnings
look solvable, but then one will eventually discover __wait_event()
and associated macros that mix when and how deeply it intentionally
shadows variables. :)

Another way to try to catch misused shadow variables is
-Wunused-but-set-varible, but it, too, has tons of false positives.

I tried to capture some of the rationale and research here:
https://github.com/KSPP/linux/issues/152

-- 
Kees Cook