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From: Emese Revfy <re.emese@gmail.com>
To: Kees Cook <keescook@chromium.org>
Cc: "kernel-hardening@lists.openwall.com"
	<kernel-hardening@lists.openwall.com>,
	PaX Team <pageexec@freemail.hu>,
	Brad Spengler <spender@grsecurity.net>,
	Michal Marek <mmarek@suse.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	linux-kbuild <linux-kbuild@vger.kernel.org>,
	minipli@ld-linux.so, Russell King <linux@armlinux.org.uk>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	David Brown <david.brown@linaro.org>,
	"benh@kernel.crashing.org" <benh@kernel.crashing.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jeff Layton <jlayton@poochiereds.net>,
	Arnd Bergmann <arnd@arndb.de>, Sam Ravnborg <sam@ravnborg.org>,
	Karsten Keil <isdn@linux-pingi.de>
Subject: [kernel-hardening] Re: [PATCH v2 1/3] Add the initify gcc plugin
Date: Wed, 13 Jul 2016 22:48:49 +0200	[thread overview]
Message-ID: <20160713224849.b42c1260b6ebb3ec1f78fa41@gmail.com> (raw)
In-Reply-To: <CAGXu5jLG6bprjCpu2oF6dexsu+8jU-WX59LY-=wUx27U459Y5Q@mail.gmail.com>

On Tue, 12 Jul 2016 15:45:56 -0400
Kees Cook <keescook@chromium.org> wrote:

> On Mon, Jul 4, 2016 at 7:40 PM, Emese Revfy <re.emese@gmail.com> wrote:
> > If a function is called by __init and __exit functions as well then
> > the plugin moves it to the __exit section. This causes false positive
> > section mismatch errors/warnings that I don't know how to handle yet.
> 
> Should the mismatch checker be updated to recognize this case? Without
> the plugin, I assume these kinds of functions would only ever be
> marked for __exit? If so, should the plugin strip the __init marking
> and only add __exit?

I don't modify the existing attributes. I just add a new __init/__exit when
a function hasn't a section attribute yet.
There are three cases:
 * when the function is called only by __init functions then the plugin adds
   the __init attribute
 * when the function is called only by __exit functions then the plugin adds
   the __exit attribute
 * when the function is called by __init and __exit functions too then the
   plugin adds the __exit attribute.
The last case causes the false positive(?) message of the section mismatch.

-- 
Emese

WARNING: multiple messages have this Message-ID (diff)
From: Emese Revfy <re.emese@gmail.com>
To: Kees Cook <keescook@chromium.org>
Cc: "kernel-hardening@lists.openwall.com"
	<kernel-hardening@lists.openwall.com>,
	PaX Team <pageexec@freemail.hu>,
	Brad Spengler <spender@grsecurity.net>,
	Michal Marek <mmarek@suse.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	linux-kbuild <linux-kbuild@vger.kernel.org>,
	minipli@ld-linux.so, Russell King <linux@armlinux.org.uk>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	David Brown <david.brown@linaro.org>,
	"benh@kernel.crashing.org" <benh@kernel.crashing.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jeff Layton <jlayton@poochiereds.net>,
	Arnd Bergmann <arnd@arndb.de>, Sam Ravnborg <sam@ravnborg.org>,
	Karsten Keil <isdn@linux-pingi.de>
Subject: Re: [PATCH v2 1/3] Add the initify gcc plugin
Date: Wed, 13 Jul 2016 22:48:49 +0200	[thread overview]
Message-ID: <20160713224849.b42c1260b6ebb3ec1f78fa41@gmail.com> (raw)
In-Reply-To: <CAGXu5jLG6bprjCpu2oF6dexsu+8jU-WX59LY-=wUx27U459Y5Q@mail.gmail.com>

On Tue, 12 Jul 2016 15:45:56 -0400
Kees Cook <keescook@chromium.org> wrote:

> On Mon, Jul 4, 2016 at 7:40 PM, Emese Revfy <re.emese@gmail.com> wrote:
> > If a function is called by __init and __exit functions as well then
> > the plugin moves it to the __exit section. This causes false positive
> > section mismatch errors/warnings that I don't know how to handle yet.
> 
> Should the mismatch checker be updated to recognize this case? Without
> the plugin, I assume these kinds of functions would only ever be
> marked for __exit? If so, should the plugin strip the __init marking
> and only add __exit?

I don't modify the existing attributes. I just add a new __init/__exit when
a function hasn't a section attribute yet.
There are three cases:
 * when the function is called only by __init functions then the plugin adds
   the __init attribute
 * when the function is called only by __exit functions then the plugin adds
   the __exit attribute
 * when the function is called by __init and __exit functions too then the
   plugin adds the __exit attribute.
The last case causes the false positive(?) message of the section mismatch.

-- 
Emese

  parent reply	other threads:[~2016-07-13 20:48 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-04 23:39 [kernel-hardening] [PATCH v2 0/3] Introduce the initify gcc plugin Emese Revfy
2016-07-04 23:39 ` Emese Revfy
2016-07-04 23:40 ` [kernel-hardening] [PATCH v2 1/3] Add " Emese Revfy
2016-07-04 23:40   ` Emese Revfy
2016-07-12 19:45   ` [kernel-hardening] " Kees Cook
2016-07-12 19:45     ` Kees Cook
2016-07-12 20:07     ` [kernel-hardening] " Emese Revfy
2016-07-12 20:07       ` Emese Revfy
2016-07-12 20:05       ` [kernel-hardening] " Kees Cook
2016-07-12 20:05         ` Kees Cook
2016-07-13 20:34         ` [kernel-hardening] " Emese Revfy
2016-07-13 20:34           ` Emese Revfy
2016-07-12 22:08     ` [kernel-hardening] " Russell King - ARM Linux
2016-07-12 22:08       ` Russell King - ARM Linux
2016-07-12 22:38       ` [kernel-hardening] " Kees Cook
2016-07-12 22:38         ` Kees Cook
2016-07-13 21:26         ` [kernel-hardening] " Emese Revfy
2016-07-13 21:26           ` Emese Revfy
2016-07-13 20:48     ` Emese Revfy [this message]
2016-07-13 20:48       ` Emese Revfy
2016-07-13 21:04       ` [kernel-hardening] " Kees Cook
2016-07-13 21:04         ` Kees Cook
2016-07-04 23:42 ` [kernel-hardening] [PATCH v2 2/3] Mark functions with the __nocapture attribute Emese Revfy
2016-07-04 23:42   ` Emese Revfy
2016-07-12 19:08   ` [kernel-hardening] " Kees Cook
2016-07-12 19:08     ` Kees Cook
2016-07-12 19:23     ` [kernel-hardening] " Daniel Micay
2016-07-12 19:47       ` Kees Cook
2016-07-04 23:43 ` [kernel-hardening] [PATCH v2 3/3] Constify some function parameters Emese Revfy
2016-07-04 23:43   ` Emese Revfy
2016-07-04 23:58   ` [kernel-hardening] " kbuild test robot
2016-07-04 23:58     ` kbuild test robot
2016-07-06 16:45     ` [kernel-hardening] " Emese Revfy
2016-07-06 16:45       ` Emese Revfy
2016-07-06 16:44   ` [kernel-hardening] " Emese Revfy
2016-07-06 16:44     ` Emese Revfy

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