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From:   Arnd Bergmann <arnd@kernel.org>
To:     linux-kernel@vger.kernel.org
Cc:     Arnd Bergmann <arnd@arndb.de>, Kees Cook <keescook@chromium.org>,
        Brendan Higgins <brendanhiggins@google.com>,
        Shuah Khan <skhan@linuxfoundation.org>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Alan Maguire <alan.maguire@oracle.com>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        Vitor Massaru Iha <vitor@massaru.org>,
        linux-hardening@vger.kernel.org, linux-kselftest@vger.kernel.org,
        kunit-dev@googlegroups.com
Subject: [RFC 0/3] kunit vs structleak
Date:   Mon, 25 Jan 2021 13:45:25 +0100
Message-Id: <20210125124533.101339-1-arnd@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Arnd Bergmann <arnd@arndb.de>

I ran into a couple of problems with kunit tests taking too much stack
space, sometimes dangerously so. These the the three instances that
cause an increase over the warning limit of some architectures:

lib/bitfield_kunit.c:93:1: error: the frame size of 7440 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]
drivers/base/test/property-entry-test.c:481:1: error: the frame size of 2640 bytes is larger than 2048 bytes [-Werror=frame-larger-than=]
drivers/thunderbolt/test.c:1529:1: error: the frame size of 1176 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

Ideally there should be a way to rewrite the kunit infrastructure
that avoids the explosion of stack data when the structleak plugin
is used.

A rather drastic measure would be to use Kconfig logic to make
the two options mutually exclusive. This would clearly work, but
is probably not needed.

As a simpler workaround, this disables the plugin for the three
files in which the excessive stack usage was observed.

      Arnd

Arnd Bergmann (3):
  bitfield: build kunit tests without structleak plugin
  drivers/base: build kunit tests without structleak plugin
  thunderbolt: build kunit tests without structleak plugin

 drivers/base/test/Makefile   | 1 +
 drivers/thunderbolt/Makefile | 1 +
 lib/Makefile                 | 1 +
 3 files changed, 3 insertions(+)

Cc: Kees Cook <keescook@chromium.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Vitor Massaru Iha <vitor@massaru.org>
Cc: linux-hardening@vger.kernel.org
Cc: linux-kselftest@vger.kernel.org
Cc: kunit-dev@googlegroups.com
Cc: linux-kernel@vger.kernel.org
-- 
2.29.2