[vlc-devel] [PATCH] add libfuzzer support

[Hugo Beauzée-Luyssen]

On Wed, Jun 21, 2017, at 03:25 PM, Shaleen Jain wrote:
> 
> On Wed, Jun 21, 2017 at 6:16 PM, Hugo Beauzée-Luyssen 
> <hugo at beauzee.fr> wrote:
> > Hi,
> > 
> > On Wed, Jun 21, 2017, at 02:36 PM, Shaleen Jain wrote:
> >>  ---
> >>   .gitignore            |  1 +
> >>   configure.ac          |  8 ++++++++
> >>   test/Makefile.am      |  2 ++
> >>   test/fuzz/Makefile.am | 19 +++++++++++++++++++
> >>   4 files changed, 30 insertions(+)
> >>   create mode 100644 test/fuzz/Makefile.am
> >> 
> >>  diff --git a/.gitignore b/.gitignore
> >>  index 0b0ee9cc20..fcd0e59213 100644
> >>  --- a/.gitignore
> >>  +++ b/.gitignore
> >>  @@ -45,6 +45,7 @@ wxvlc
> >>   vlc_install_dir/*
> >>   plugins.dat
> >>   patches/*
> >>  +*_fuzzer
> >> 
> >>   include/vlc/libvlc_version.h
> >> 
> >>  diff --git a/configure.ac b/configure.ac
> >>  index 67fc7deb1a..c289b69510 100644
> >>  --- a/configure.ac
> >>  +++ b/configure.ac
> >>  @@ -94,6 +94,13 @@ AS_IF([test -n "${with_binary_version}"],[
> >>            [Binary specific version])
> >>   ])
> >> 
> >>  +AC_COMPILE_IFELSE([AC_LANG_PROGRAM([], [
> >>  +#if !defined(__clang__)
> >>  +#error
> >>  +#endif])], have_clang=yes, have_clang=no)
> >>  +
> >>  +AM_CONDITIONAL(HAVE_CLANG, test "x$have_clang" = "xyes")
> >>  +
> > 
> > As pointed out by Marvin, it would be more idiomatic to use
> > ax_check_compile_flag (or something similar) to enable flags
> > conditionally.
> 
> I don't think it would be worth adding a 75 line marco for a flag that 
> is used
> only maybe once, plus it not anymore idiomatic than ac_compile_ifelse

Check RDC_PROG_CC_FLAGS in VLC then.

> > 
> > 
> >>   dnl
> >>   dnl  Check the operating system
> >>   dnl
> >>  @@ -4248,6 +4255,7 @@ AC_CONFIG_FILES([
> >>     lib/Makefile
> >>     bin/Makefile
> >>     test/Makefile
> >>  +  test/fuzz/Makefile
> >>     modules/hw/mmal/Makefile
> >>     share/vlc.appdata.xml.in
> >>   ])
> >>  diff --git a/test/Makefile.am b/test/Makefile.am
> >>  index 95d4df6516..30c1bb56b6 100644
> >>  --- a/test/Makefile.am
> >>  +++ b/test/Makefile.am
> >>  @@ -4,6 +4,8 @@
> >> 
> >>   AUTOMAKE_OPTIONS = subdir-objects
> >> 
> >>  +SUBDIRS = fuzz
> >>  +
> >>   extra_check_verbose = $(extra_check_verbose_$(V))
> >>   extra_check_verbose_ = 
> >> $(extra_check_flags__$(AM_DEFAULT_VERBOSITY))
> >>   extra_check_verbose_0 = @echo TEST $@
> >>  diff --git a/test/fuzz/Makefile.am b/test/fuzz/Makefile.am
> >>  new file mode 100644
> >>  index 0000000000..57eb04f13f
> >>  --- /dev/null
> >>  +++ b/test/fuzz/Makefile.am
> >>  @@ -0,0 +1,19 @@
> >>  +AUTOMAKE_OPTIONS = subdir-objects
> >>  +
> >>  +AM_CXXFLAGS = -fsanitize=address -fsanitize-address-use-after-scope
> >>  -fsanitize=undefined -fno-sanitize-recover=undefined
> >>  +if HAVE_CLANG
> >>  +AM_CXXFLAGS += -fsanitize-coverage=trace-pc-guard,trace-cmp
> >>  +else
> >>  +AM_CXXFLAGS += -fsanitize-coverage=trace-pc
> >>  +endif
> >>  +
> >>  +LIBVLCCORE = ../../src/libvlccore.la
> >>  +LIBVLC = ../../lib/libvlc.la
> >>  +
> >>  +LDADD = $(LIBVLCCORE) $(LIBVLC) -L./ -lFuzzer
> > 
> > You need to check for libfuzzer presence in the configure. Also, I'm 
> > not
> > sure running fuzz testing for each 'make check' is a good idea.
> > I'm not sure what would be the best way to do this, but I'd be in 
> > favor
> > of a separate target. Fuzz testing will most likely be quite long at
> > some point, and we don't want to make all our source builds that run
> > make check/make distcheck last for many hours.
> 
> make check will only build the fuzz binaries, not run them.
> > 
> > 
> >>  +
> >>  +check_PROGRAMS = \
> >>  +       libvlc_demux_fuzzer
> >>  +
> >>  +libvlc_demux_fuzzer_SOURCES = libvlc_demux_fuzzer.cpp
> > 
> > I think you forgot to add the file :)
> 
> No, I planned to push a separate patch for that, which I did a few 
> minutes ago.

If you add a reference to a file in the makefile, then you must add the
file in the same commit, otherwise the build will be broken.

> > 
> > 
> >>  +
> >>  --
> >>  2.13.1
> >> 
> >>  _______________________________________________
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> > 
> > 
> > --
> >   Hugo Beauzée-Luyssen
> >   hugo at beauzee.fr
> > _______________________________________________
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> 
> 
> 
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-- 
  Hugo Beauzée-Luyssen
  hugo at beauzee.fr