Re: [PATCH v2 1/2] Add libfuzzer target to fuzz/x86_instruction_emulator

[Tamas K Lengyel <tamas@xxxxxxxxxxxxx>]

On Mon, Jul 22, 2024 at 7:08 AM Jan Beulich <jbeulich@xxxxxxxx> wrote:
>
> On 22.07.2024 13:03, Tamas K Lengyel wrote:
> > On Mon, Jul 22, 2024 at 5:20 AM Jan Beulich <jbeulich@xxxxxxxx> wrote:
> >>
> >> On 26.06.2024 00:47, Tamas K Lengyel wrote:
> >>> This target enables integration into oss-fuzz. Changing invalid input 
> >>> return
> >>> to -1 as values other then 0/-1 are reserved by libfuzzer. Also adding the
> >>> missing __wrap_vsnprintf wrapper which is required for successful oss-fuzz
> >>> build.
> >>>
> >>> Signed-off-by: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>
> >>
> >> I've reverted this right away, because of ...
> >>
> >>> @@ -58,6 +58,9 @@ afl-harness: afl-harness.o $(OBJS) cpuid.o wrappers.o
> >>>  afl-harness-cov: afl-harness-cov.o $(patsubst %.o,%-cov.o,$(OBJS)) 
> >>> cpuid.o wrappers.o
> >>>       $(CC) $(CFLAGS) $(GCOV_FLAGS) $(addprefix 
> >>> -Wl$(comma)--wrap=,$(WRAPPED)) $^ -o $@
> >>>
> >>> +libfuzzer-harness: $(OBJS) cpuid.o wrappers.o
> >>> +     $(CC) $(CFLAGS) $(LIB_FUZZING_ENGINE) -fsanitize=fuzzer $(addprefix 
> >>> -Wl$(comma)--wrap=,$(WRAPPED)) $^ -o $@
> >>
> >> ... this causing
> >>
> >> gcc: error: unrecognized argument to '-fsanitize=' option: 'fuzzer'
> >> make[6]: *** [Makefile:62: libfuzzer-harness] Error 1
> >>
> >> with apparently a fair set of gcc-s used by distro-s we use for CI.
> >
> > Well let me see if I can hack the Makefile to only build this with clang..
>
> Oh, and - please don't special case Clang. Instead please check for option
> availability (e.g. using cc-option), such that for possible future gcc,
> when support there may have been added, we'd then build it there as well.

I decided to just not include the libfuzzer harness in the default 'all' target.

Tamas