[ovs-dev] [PATCH] oss-fuzz: Move oss-fuzz test harnesses and fuzzer configs to ovs source repo

Bhargava Shastry bshastry at sect.tu-berlin.de
Mon Jul 30 09:58:07 UTC 2018


Any updates on the proposed patch? :-)

On 07/16/2018 02:07 PM, Bhargava Shastry wrote:
> Update: I fixed these errors in the attached patch that supersedes the
> patch here (https://patchwork.ozlabs.org/patch/942118/)
> 
> The major change is that I add the following line for each fuzz target
> binary in the tests/oss-fuzz/automake.mk file:
> 
> e.g.,
> tests_oss_fuzz_flow_extract_target_LDFLAGS = $(LIB_FUZZING_ENGINE) \
>                                             -lc++
> 
> Regards,
> Bhargava
> 
> On 07/16/2018 11:45 AM, Bhargava Shastry wrote:
>> Oops, here's the link failure log:
>>
>> ```
>> /usr/lib/gcc/x86_64-linux-gnu/5.4.0/../../../x86_64-linux-gnu/crt1.o: In
>> function `_start':
>> (.text+0x20): undefined reference to `main'
>> clang-7: error: linker command failed with exit code 1 (use -v to see
>> invocation)
>> Makefile:4159: recipe for target 'tests/oss-fuzz/flow_extract_target' failed
>> make: *** [tests/oss-fuzz/flow_extract_target] Error 1
>> fuzzers build failed.
>> ```
>>
>> The main symbol is provided by libfuzzer (clang++ -lFuzzingEngine)
>>
>> Regards,
>> Bhargava
>>
>> On 07/16/2018 11:36 AM, Bhargava Shastry wrote:
>>> Hi Ben,
>>>
>>>> Never mind that one, I failed to check in some of that.
>>>>
>>>> I sent it formally:
>>>>         https://patchwork.ozlabs.org/patch/942118/
>>>
>>> Thanks for the patch. This fixes the previous error. Now, there are some
>>> new errors during the compilation/linking process. I think most of this
>>> can be fixed if I figure out how automake works. In a nutshell, here's
>>> the problem:
>>>
>>> - oss-fuzz provides compilation flags that can be plugged in like so
>>> ```
>>> CC=clang
>>> CXX=clang++
>>> CFLAGS=-O1 -fno-omit-frame-pointer -gline-tables-only
>>> -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION -fsanitize=address
>>> -fsanitize-address-use-after-scope -fsanitize=fuzzer-no-link
>>> CXXFLAGS=-O1 -fno-omit-frame-pointer -gline-tables-only
>>> -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION -fsanitize=address
>>> -fsanitize-address-use-after-scope -fsanitize=fuzzer-no-link -stdlib=libc++
>>> ```
>>>
>>> And here's what I used to do before
>>>
>>> - Use clang and CFLAGS above plus some additional includes to compile
>>> each of the fuzzer tests
>>> - Use clang++ and additional linker flags to link these into a fuzzer binary
>>>
>>> Now, I see that the compilation works
>>> ```
>>> depbase=`echo tests/oss-fuzz/flow_extract_target.o | sed
>>> 's|[^/]*$|.deps/&|;s|\.o$||'`;\
>>> clang -DHAVE_CONFIG_H -I.    -I ./include -I ./include -I ./lib -I ./lib
>>> -I/usr/include   -Wstrict-prototypes -Wall -Wextra -Wno-sign-compare
>>> -Wpointer-arith -Wformat -Wformat-security -Wswitch-enum
>>> -Wunused-parameter -Wbad-function-cast -Wcast-align -Wstrict-prototypes
>>> -Wold-style-definition -Wmissing-prototypes -Wmissing-field-initializers
>>> -Wthread-safety -fno-strict-aliasing -Wswitch-bool
>>> -Wlogical-not-parentheses -Wsizeof-array-argument -Wshift-negative-value
>>> -Qunused-arguments -Wshadow -Wno-null-pointer-arithmetic    -O1
>>> -fno-omit-frame-pointer -gline-tables-only
>>> -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION -fsanitize=address
>>> -fsanitize-address-use-after-scope -fsanitize=fuzzer-no-link -MT
>>> tests/oss-fuzz/flow_extract_target.o -MD -MP -MF $depbase.Tpo -c -o
>>> tests/oss-fuzz/flow_extract_target.o
>>> tests/oss-fuzz/flow_extract_target.c &&\
>>> mv -f $depbase.Tpo $depbase.Po
>>> ```
>>>
>>> However, the linking fails
>>> ```
>>> libtool: link: clang -Wstrict-prototypes -Wall -Wextra -Wno-sign-compare
>>> -Wpointer-arith -Wformat -Wformat-security -Wswitch-enum
>>> -Wunused-parameter -Wbad-function-cast -Wcast-align -Wstrict-prototypes
>>> -Wold-style-definition -Wmissing-prototypes -Wmissing-field-initializers
>>> -Wthread-safety -fno-strict-aliasing -Wswitch-bool
>>> -Wlogical-not-parentheses -Wsizeof-array-argument -Wshift-negative-value
>>> -Qunused-arguments -Wshadow -Wno-null-pointer-arithmetic -O1
>>> -fno-omit-frame-pointer -gline-tables-only
>>> -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION -fsanitize=address
>>> -fsanitize-address-use-after-scope -fsanitize=fuzzer-no-link -o
>>> tests/oss-fuzz/flow_extract_target tests/oss-fuzz/flow_extract_target.o
>>> -L/usr/lib lib/.libs/libopenvswitch.a -lssl -lcrypto -latomic
>>> ```
>>>
>>> I think adding -lFuzzingEngine should fix this but another variable
>>> between my build script and automake is the use of clang++ for linking.
>>>
>>> Do you know how I can experiment with different linker flags and
>>> compiler/linker in automake?
>>>
>>> Regards,
>>> Bhargava
>>>
>>>
>>
> 

-- 
Bhargava Shastry <bshastry at sect.tu-berlin.de>
Security in Telecommunications
TU Berlin / Telekom Innovation Laboratories
Ernst-Reuter-Platz 7, Sekr TEL 17 / D - 10587 Berlin, Germany
phone: +49 30 8353 58235
Keybase: https://keybase.io/bshastry


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