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From: Jann Horn <jannh@google.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: dev@openvswitch.org, Kees Cook <keescook@chromium.org>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Network Development <netdev@vger.kernel.org>,
	intel-gfx@lists.freedesktop.org, linux-usb@vger.kernel.org,
	kernel list <linux-kernel@vger.kernel.org>,
	dri-devel@lists.freedesktop.org, Linux-MM <linux-mm@kvack.org>,
	linux-security-module <linux-security-module@vger.kernel.org>,
	Kernel Hardening <kernel-hardening@lists.openwall.com>,
	intel-wired-lan@lists.osuosl.org, linux-fsdevel@vger.kernel.org,
	xen-devel <xen-devel@lists.xenproject.org>,
	Laura Abbott <labbott@redhat.com>,
	linux-kbuild@vger.kernel.org,
	Alexander Popov <alex.popov@linux.com>
Subject: Re: [PATCH 1/3] treewide: Lift switch variables out of switches
Date: Wed, 23 Jan 2019 13:09:13 +0100	[thread overview]
Message-ID: <CAG48ez2vfXkr9dozJiGmze8k49VOXfs=K7M8bv0aQsDDpzrEFQ__7093.22736818052$1548245449$gmane$org@mail.gmail.com> (raw)
In-Reply-To: <20190123115829.GA31385@kroah.com>

On Wed, Jan 23, 2019 at 1:04 PM 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?

AFAICS this only applies to switch statements (because they jump to a
case and don't execute stuff at the start of the block), not blocks
after if/while/... .

> That's going to be a hard thing to keep from happening over time, as
> this is valid C :(

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  reply	other threads:[~2019-01-23 12:09 UTC|newest]

Thread overview: 96+ 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 ` [Intel-wired-lan] " Kees Cook
2019-01-23 11:03 ` [PATCH 1/3] treewide: Lift switch variables out of switches Kees Cook
2019-01-23 11:03 ` Kees Cook
2019-01-23 11:03   ` [Intel-wired-lan] " Kees Cook
2019-01-23 11:03   ` Kees Cook
2019-01-23 11:03   ` [1/3] " Kees Cook
2019-01-23 11:58   ` [PATCH 1/3] " Greg KH
2019-01-23 11:58   ` Greg KH
2019-01-23 11:58     ` [Intel-wired-lan] " Greg KH
2019-01-23 11:58     ` [1/3] " Greg Kroah-Hartman
2019-01-23 12:09     ` Jann Horn [this message]
2019-01-23 12:09     ` [PATCH 1/3] " Jann Horn
2019-01-23 12:09       ` [Intel-wired-lan] " Jann Horn
2019-01-23 12:09       ` Jann Horn
2019-01-23 12:09       ` [1/3] " Jann Horn
2019-01-23 12:12       ` [PATCH 1/3] " Ard Biesheuvel
2019-01-23 12:12       ` Ard Biesheuvel
2019-01-23 12:12         ` [Intel-wired-lan] " Ard Biesheuvel
2019-01-23 12:12         ` Ard Biesheuvel
2019-01-23 12:12         ` [1/3] " Ard Biesheuvel
2019-01-23 13:21       ` [PATCH 1/3] " William Kucharski
2019-01-23 13:21       ` William Kucharski
2019-01-23 13:21         ` [Intel-wired-lan] " William Kucharski
2019-01-23 13:21         ` [1/3] " William Kucharski
2019-01-23 14:17     ` [Intel-gfx] [PATCH 1/3] " Jani Nikula
2019-01-23 14:17       ` [Intel-wired-lan] " Jani Nikula
2019-01-23 14:17       ` Jani Nikula
2019-01-23 14:17       ` [1/3] " Jani Nikula
2019-01-23 14:23       ` [Intel-gfx] [PATCH 1/3] " Jani Nikula
2019-01-23 14:23       ` Jani Nikula
2019-01-23 14:23         ` [Intel-wired-lan] " Jani Nikula
2019-01-23 14:23         ` [1/3] " Jani Nikula
2019-01-23 14:47       ` [Intel-gfx] [PATCH 1/3] " Edwin Zimmerman
2019-01-23 14:47         ` [Intel-wired-lan] " Edwin Zimmerman
2019-01-23 14:47         ` Edwin Zimmerman
2019-01-23 14:47         ` [1/3] " Edwin Zimmerman
2019-01-23 14:47         ` [Intel-gfx] [PATCH 1/3] " Edwin Zimmerman
2019-01-23 15:46         ` Jani Nikula
2019-01-23 15:46         ` Jani Nikula
2019-01-23 15:46           ` [Intel-wired-lan] " Jani Nikula
2019-01-23 15:46           ` Jani Nikula
2019-01-23 15:46           ` [1/3] " Jani Nikula
2019-01-23 18:55           ` [Intel-gfx] [PATCH 1/3] " Kees Cook
2019-01-23 18:55             ` [Intel-wired-lan] " Kees Cook
2019-01-23 18:55             ` Kees Cook
2019-01-23 18:55             ` [1/3] " Kees Cook
2019-01-23 18:55             ` [Intel-gfx] [PATCH 1/3] " Kees Cook
2019-01-24  8:10             ` Greg KH
2019-01-24  8:10             ` Greg KH
2019-01-24  8:10               ` [Intel-wired-lan] " Greg KH
2019-01-24  8:10               ` [1/3] " Greg Kroah-Hartman
2019-01-24  8:10               ` [Intel-gfx] [PATCH 1/3] " Greg KH
2019-01-23 18:55           ` Kees Cook
2019-01-23 19:18       ` Matthew Wilcox
2019-01-23 19:18         ` [Intel-wired-lan] " Matthew Wilcox
2019-01-23 19:18         ` [1/3] " Matthew Wilcox
2019-01-23 20:36         ` [Intel-gfx] [PATCH 1/3] " Kees Cook
2019-01-23 20:36         ` Kees Cook
2019-01-23 20:36           ` [Intel-wired-lan] " Kees Cook
2019-01-23 20:36           ` Kees Cook
2019-01-23 20:36           ` [1/3] " Kees Cook
2019-01-23 20:36           ` [Intel-gfx] [PATCH 1/3] " Kees Cook
2019-01-23 19:18       ` Matthew Wilcox
2019-01-23 14:17     ` Jani Nikula
2019-01-23 16:51   ` [Intel-wired-lan] " Jeff Kirsher
2019-01-23 16:51     ` Jeff Kirsher
2019-01-23 16:51     ` Jeff Kirsher
2019-01-23 16:51     ` [1/3] " Jeff Kirsher
2019-01-23 16:51   ` [Intel-wired-lan] [PATCH 1/3] " Jeff Kirsher
2019-01-24 12:58   ` Edwin Zimmerman
2019-01-24 12:58     ` [Intel-wired-lan] " Edwin Zimmerman
2019-01-24 12:58     ` [1/3] " Edwin Zimmerman
2019-01-24 12:58     ` [PATCH 1/3] " Edwin Zimmerman
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   ` [Intel-wired-lan] " Kees Cook
2019-01-23 11:03   ` Kees Cook
2019-01-23 11:03   ` [2/3] " Kees Cook
2019-01-23 11:03 ` [PATCH 2/3] " Kees Cook
2019-01-23 11:03 ` [PATCH 3/3] lib: Introduce test_stackinit module Kees Cook
2019-01-23 11:03   ` [Intel-wired-lan] " Kees Cook
2019-01-23 11:03   ` Kees Cook
2019-01-23 11:03   ` [3/3] " Kees Cook
2019-01-23 11:03 ` [PATCH 3/3] " Kees Cook
2019-01-23 11:20 ` ✗ Fi.CI.BAT: failure for gcc-plugins: Introduce stackinit plugin Patchwork
2019-01-23 14:26   ` Jani Nikula
2019-01-29  0:12 ` [PATCH 0/3] " Alexander Popov
2019-01-29  0:12 ` Alexander Popov
2019-01-29  0:12   ` [Intel-wired-lan] " Alexander Popov
2019-02-12 17:54   ` Kees Cook
2019-02-12 17:54   ` Kees Cook
2019-02-12 17:54     ` [Intel-wired-lan] " Kees Cook
2019-02-12 17:54     ` Kees Cook
2019-02-12 17:54     ` Kees Cook
2019-02-12 17:54     ` Kees Cook

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