From: "Philippe Mathieu-Daudé" <f4bug@amsat.org>
To: Alexander Bulekov <alxndr@bu.edu>, qemu-devel@nongnu.org
Subject: Re: [PATCH 2/4] fuzz: add an instrumentation filter
Date: Fri, 18 Jun 2021 09:20:18 +0200 [thread overview]
Message-ID: <638771e2-b945-a136-95cf-9ef58e22bc34@amsat.org> (raw)
In-Reply-To: <20210617195353.284082-3-alxndr@bu.edu>
On 6/17/21 9:53 PM, Alexander Bulekov wrote:
> By default, -fsanitize=fuzzer instruments all code with coverage
> information. However, this means that libfuzzer will track coverage over
> hundreds of source files that are unrelated to virtual-devices. This
> means that libfuzzer will optimize inputs for coverage observed in timer
> code, memory APIs etc. This slows down the fuzzer and stores many inputs
> that are not relevant to the actual virtual-devices.
>
> With this change, clang will only instrument a subset of the compiled
> code, that is directly related to virtual-devices.
>
> Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
> ---
> configure | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/configure b/configure
> index debd50c085..40412bcfcf 100755
> --- a/configure
> +++ b/configure
> @@ -6089,6 +6089,10 @@ if test "$fuzzing" = "yes" ; then
> # If LIB_FUZZING_ENGINE is set, assume we are running on OSS-Fuzz, and the
> # needed CFLAGS have already been provided
> if test -z "${LIB_FUZZING_ENGINE+xxx}" ; then
> + # Specify a filter to only instrument code that is directly related to
> + # virtual-devices.
> + QEMU_CFLAGS="$QEMU_CFLAGS -fsanitize-coverage-allowlist=$source_path/scripts/oss-fuzz/instrumentation-filter"
I'm getting:
cannot access 'scripts/oss-fuzz/instrumentation-filter': No such file or
directory
Did you forgot to add the file, or is this series based on another one?
Regards,
Phil.
next prev parent reply other threads:[~2021-06-18 7:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-17 19:53 [PATCH 0/4] Miscellaneous fuzzer changes Alexander Bulekov
2021-06-17 19:53 ` [PATCH 1/4] fuzz: adjust timeout to allow for longer inputs Alexander Bulekov
2021-06-17 19:53 ` [PATCH 2/4] fuzz: add an instrumentation filter Alexander Bulekov
2021-06-18 7:20 ` Philippe Mathieu-Daudé [this message]
2021-06-17 19:53 ` [PATCH 3/4] fuzz: fix the AC97 generic-fuzzer config Alexander Bulekov
2021-06-17 19:53 ` [PATCH 4/4] fuzz: fix the ES1370 " Alexander Bulekov
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