From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from eggs.gnu.org ([208.118.235.92]:45251)
	by lists.gnu.org with esmtp (Exim 4.71)
	(envelope-from <armbru@redhat.com>) id 1UdHVp-0001Yv-VN
	for qemu-devel@nongnu.org; Fri, 17 May 2013 06:03:50 -0400
Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71)
	(envelope-from <armbru@redhat.com>) id 1UdHVl-00032H-5V
	for qemu-devel@nongnu.org; Fri, 17 May 2013 06:03:45 -0400
Received: from mx1.redhat.com ([209.132.183.28]:61225)
	by eggs.gnu.org with esmtp (Exim 4.71)
	(envelope-from <armbru@redhat.com>) id 1UdHMd-00089P-Qt
	for qemu-devel@nongnu.org; Fri, 17 May 2013 05:54:16 -0400
Received: from int-mx10.intmail.prod.int.phx2.redhat.com
	(int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23])
	by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r4H9sERv026130
	(version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK)
	for <qemu-devel@nongnu.org>; Fri, 17 May 2013 05:54:15 -0400
From: Markus Armbruster <armbru@redhat.com>
References: <1368780720-14852-1-git-send-email-stefanha@redhat.com>
Date: Fri, 17 May 2013 11:54:12 +0200
In-Reply-To: <1368780720-14852-1-git-send-email-stefanha@redhat.com> (Stefan
	Hajnoczi's message of "Fri, 17 May 2013 10:52:00 +0200")
Message-ID: <87obcaaq4b.fsf@blackfin.pond.sub.org>
MIME-Version: 1.0
Content-Type: text/plain
Subject: Re: [Qemu-devel] [PATCH] tests: set MALLOC_PERTURB_ to expose
	memory bugs
List-Id: <qemu-devel.nongnu.org>
List-Unsubscribe: <https://lists.nongnu.org/mailman/options/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.nongnu.org/archive/html/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <https://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Lucas Meneghel Rodrigues <lmr@redhat.com>, qemu-devel@nongnu.org

Stefan Hajnoczi <stefanha@redhat.com> writes:

> glibc wipes malloc(3) memory when the MALLOC_PERTURB_ environment
> variable is set.  The value of the environment variable determines the
> bit pattern used to wipe memory.  For more information, see
> http://udrepper.livejournal.com/11429.html.
>
> Set MALLOC_PERTURB_ for gtester and qemu-iotests.  Note we always set
> the environment variable to 1 so the test is deterministic.  Setting a
> random variable might expose more bugs but would be harder to reproduce.
>
> Both make check and qemu-iotests pass with MALLOC_PERTURB_ enabled.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> Lucas noticed KVM autotest failures when enabling MALLOC_PERTURB_.  By enabling
> it for in-tree test suites we can detect memory management errors earlier.
>
>  tests/Makefile           | 4 +++-
>  tests/qemu-iotests/check | 2 +-
>  2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/tests/Makefile b/tests/Makefile
> index a307d5a..25f6d28 100644
> --- a/tests/Makefile
> +++ b/tests/Makefile
> @@ -171,6 +171,7 @@ GCOV_OPTIONS = -n $(if $(V),-f,)
>  $(patsubst %, check-qtest-%, $(QTEST_TARGETS)): check-qtest-%: $(check-qtest-y)
>  	$(if $(CONFIG_GCOV),@rm -f *.gcda */*.gcda */*/*.gcda */*/*/*.gcda,)
>  	$(call quiet-command,QTEST_QEMU_BINARY=$*-softmmu/qemu-system-$* \
> +		MALLOC_PERTURB_=1 \
>  		gtester $(GTESTER_OPTIONS) -m=$(SPEED) $(check-qtest-$*-y),"GTESTER $@")
>  	$(if $(CONFIG_GCOV),@for f in $(gcov-files-$*-y); do \
>  	  echo Gcov report for $$f:;\

If you want punishment, why not go for extra punishment?

MALLOC_PERTURB_=$(($RANDOM % 255 + 1))

[...]