Re: [PATCH 2/4] fuzz: add an instrumentation filter

[Philippe Mathieu-Daudé]

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.