From: Jani Nikula <jani.nikula@linux.intel.com>
To: Edwin Zimmerman <edwin@211mainstreet.net>,
'Greg KH' <gregkh@linuxfoundation.org>,
'Kees Cook' <keescook@chromium.org>
Cc: dev@openvswitch.org, 'Ard Biesheuvel' <ard.biesheuvel@linaro.org>,
netdev@vger.kernel.org, intel-gfx@lists.freedesktop.org,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
dri-devel@lists.freedesktop.org, linux-mm@kvack.org,
linux-security-module@vger.kernel.org,
kernel-hardening@lists.openwall.com,
intel-wired-lan@lists.osuosl.org, linux-fsdevel@vger.kernel.org,
xen-devel@lists.xenproject.org,
'Laura Abbott' <labbott@redhat.com>,
linux-kbuild@vger.kernel.org,
'Alexander Popov' <alex.popov@linux.com>
Subject: RE: [Intel-gfx] [PATCH 1/3] treewide: Lift switch variables out of switches
Date: Wed, 23 Jan 2019 17:46:14 +0200 [thread overview]
Message-ID: <87va2f1int.fsf@intel.com> (raw)
In-Reply-To: <000001d4b32a$845e06e0$8d1a14a0$@211mainstreet.net>
On Wed, 23 Jan 2019, Edwin Zimmerman <edwin@211mainstreet.net> wrote:
> On Wed, 23 Jan 2019, Jani Nikula <jani.nikula@linux.intel.com> wrote:
>> On Wed, 23 Jan 2019, Greg KH <gregkh@linuxfoundation.org> wrote:
>> > On Wed, Jan 23, 2019 at 03:03:47AM -0800, Kees Cook wrote:
>> >> Variables declared in a switch statement before any case statements
>> >> cannot be initialized, so move all instances out of the switches.
>> >> After this, future always-initialized stack variables will work
>> >> and not throw warnings like this:
>> >>
>> >> fs/fcntl.c: In function ‘send_sigio_to_task’:
>> >> fs/fcntl.c:738:13: warning: statement will never be executed [-Wswitch-unreachable]
>> >> siginfo_t si;
>> >> ^~
>> >
>> > That's a pain, so this means we can't have any new variables in { }
>> > scope except for at the top of a function?
>> >
>> > That's going to be a hard thing to keep from happening over time, as
>> > this is valid C :(
>>
>> Not all valid C is meant to be used! ;)
>
> Very true. The other thing to keep in mind is the burden of enforcing
> a prohibition on a valid C construct like this. It seems to me that
> patch reviewers and maintainers have enough to do without forcing them
> to watch for variable declarations in switch statements. Automating
> this prohibition, should it be accepted, seems like a good idea to me.
Considering that the treewide diffstat to fix this is:
18 files changed, 45 insertions(+), 46 deletions(-)
and using the gcc plugin in question will trigger the switch-unreachable
warning, I think we're good. There'll probably be the occasional
declarations that pass through, and will get fixed afterwards.
BR,
Jani.
--
Jani Nikula, Intel Open Source Graphics Center
next prev parent reply other threads:[~2019-01-23 15:46 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-23 11:03 [PATCH 0/3] gcc-plugins: Introduce stackinit plugin Kees Cook
2019-01-23 11:03 ` [PATCH 1/3] treewide: Lift switch variables out of switches Kees Cook
2019-01-23 11:58 ` Greg KH
2019-01-23 12:09 ` Jann Horn
2019-01-23 12:12 ` Ard Biesheuvel
2019-01-23 13:21 ` William Kucharski
2019-01-23 14:17 ` [Intel-gfx] " Jani Nikula
2019-01-23 14:23 ` Jani Nikula
2019-01-23 14:47 ` Edwin Zimmerman
2019-01-23 15:46 ` Jani Nikula [this message]
2019-01-23 18:55 ` Kees Cook
2019-01-24 8:10 ` Greg KH
2019-01-23 19:18 ` Matthew Wilcox
2019-01-23 20:36 ` Kees Cook
2019-01-23 16:51 ` [Intel-wired-lan] " Jeff Kirsher
2019-01-24 12:58 ` Edwin Zimmerman
2019-01-23 11:03 ` [PATCH 2/3] gcc-plugins: Introduce stackinit plugin Kees Cook
2019-01-23 11:03 ` [PATCH 3/3] lib: Introduce test_stackinit module Kees Cook
2019-01-29 0:12 ` [PATCH 0/3] gcc-plugins: Introduce stackinit plugin Alexander Popov
2019-02-12 17:54 ` Kees Cook
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87va2f1int.fsf@intel.com \
--to=jani.nikula@linux.intel.com \
--cc=alex.popov@linux.com \
--cc=ard.biesheuvel@linaro.org \
--cc=dev@openvswitch.org \
--cc=dri-devel@lists.freedesktop.org \
--cc=edwin@211mainstreet.net \
--cc=gregkh@linuxfoundation.org \
--cc=intel-gfx@lists.freedesktop.org \
--cc=intel-wired-lan@lists.osuosl.org \
--cc=keescook@chromium.org \
--cc=kernel-hardening@lists.openwall.com \
--cc=labbott@redhat.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kbuild@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-security-module@vger.kernel.org \
--cc=linux-usb@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=xen-devel@lists.xenproject.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).