Add Exiv2

[kevinbackhouse]

Exiv2 is a command-line utility and C++ library for reading, writing, deleting, and modifying the metadata of image files. It would be great if you could add it to OSS-Fuzz!

I have fixed all the ASAN/UBSAN bugs that I am aware of. However, there are a few results like this, which I consider to be false positives:

/home/kev/exiv2/src/tiffvisitor_int.cpp:778:29: runtime error: null pointer passed as argument 2, which is declared to never be null
/usr/include/string.h:44:28: note: nonnull attribute specified here
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior /home/kev/exiv2_0.27/src/tiffvisitor_int.cpp:778:29 in 

That error is due to calling memcpy() with a null pointer, but the size argument is zero, so I don't think it's a bug. The issue is discussed here on stackoverflow. Will that be a problem on OSS-Fuzz? If so, I will postpone this pull request until I have fixed those issues. (I am planning to do so anyway, but I am keen to get Exiv2 enrolled in OSS-Fuzz as soon as possible.)

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[kevinbackhouse]

@googlebot I signed it!

[kevinbackhouse]

Please could you try running the checks again? I have made some changes and tested locally using these instructions.

[jonathanmetzman]

Done.

[kevinbackhouse]

I dropped AFL and honggfuzz, so the checks pass now. (I tested it on my own fork.) In the previous commit, I got the AFL build to pass by changing the way that I create the seed corpus, but honggfuzz was still failing with the message "ERROR: 100.0% of fuzz targets seem to be broken". Our fuzz target uses LLVMFuzzerTestOneInput, so our cmake build uses -fsanitize=fuzzer-no-link and -fsanitize=fuzzer. I guess those are libFuzzer features that shouldn't be used with AFL and honggfuzz, but I am not sure how to build the fuzzing target without them (there would be no main function). So the easiest solution is to drop AFL and honggfuzz, but please let me know if you have any advice on how to make our build system compatible with them.

[inferno-chromium]

I dropped AFL and honggfuzz, so the checks pass now. (I tested it on my own fork.) In the previous commit, I got the AFL build to pass by changing the way that I create the seed corpus, but honggfuzz was still failing with the message "ERROR: 100.0% of fuzz targets seem to be broken". Our fuzz target uses LLVMFuzzerTestOneInput, so our cmake build uses -fsanitize=fuzzer-no-link and -fsanitize=fuzzer. I guess those are libFuzzer features that shouldn't be used with AFL and honggfuzz, but I am not sure how to build the fuzzing target without them (there would be no main function). So the easiest solution is to drop AFL and honggfuzz, but please let me know if you have any advice on how to make our build system compatible with them.

OSS-Fuzz passes the right cflags and cxxflags when needing to build afl++ and honggfuzz, can you avoid setting those when run in OSS-Fuzz build environment ? AFL++ coverage is important as it finds its unique set of bugs.

[kevinbackhouse]

@inferno-chromium: If I remove the -fsanitize=fuzzer flag from our cmake config then all the builds fail with the error "undefined reference to main" (link to test PR). That's because our fuzz target only defines LLVMFuzzerTestOneInput, and the main function is auto-generated by libFuzzer.

Is there a way to add a main function that is compatible with libFuzzer, AFL, and honggfuzz?

[kevinbackhouse]

Ok, apparently the solution is to add $LIB_FUZZING_ENGINE as a linker flag (link to test PR).

I have created a pull request to update our cmake configuration. When that's merged, I'll add another commit to this PR to update build.sh. I'll switch this PR to draft until that's ready.

[jonathanmetzman]

Ok, apparently the solution is to add $LIB_FUZZING_ENGINE as a linker flag (link to test PR).

I have created a pull request to update our cmake configuration. When that's merged, I'll add another commit to this PR to update build.sh. I'll switch this PR to draft until that's ready.

Right, the main function for AFL/LibFuzzer/HF is linked in via LIB_FUZZING_ENGINE

[kevinbackhouse]

This should pass the automated checks now (link to test PR).