Re: [Qemu-devel] [PATCH] tests: set MALLOC_PERTURB_ to expose memory bugs

[Markus Armbruster <armbru@redhat.com>]

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))

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