verify: libFuzzer harness for secs2::decode + try_parse_sml
Coverage-guided structural search for crashes and undefined behaviour on arbitrary input to our two parsers. What's wired: - -DSECSGEM_FUZZ=ON CMake option, clang-only. Adds -fsanitize=fuzzer-no-link,address,undefined to all targets + -fsanitize=fuzzer to the two fuzz executables. - apps/fuzz_secs2_decode.cpp — feeds raw bytes to secs2::decode. Catches secs2::CodecError (expected) but traps on anything else leaking (would be a hardening bug). - apps/fuzz_sml_parse.cpp — feeds string to try_parse_sml, which is contractually nothrow-equivalent; traps on any exception. - .gitea/workflows/ci.yml — `libfuzzer` job builds with clang and runs each fuzzer for 60s in CI. Any crash / ASan / UBSan flag fails the job. - Dockerfile gains clang + libclang-rt-18-dev so devs can run locally with the same toolchain. Result on a fresh 30-second local run: fuzz_secs2_decode: 70 727 random inputs, 0 crashes fuzz_sml_parse: 284 950 random inputs, 0 crashes The coverage-guided search found and synthesized inputs that exercise: zero-byte, single-byte format tags, all length-byte counts (1/2/3), nested lists, format bytes with reserved bits, the "BOOLEAN" SML token, malformed quoted strings, etc. libFuzzer's recommended dictionary at the end of each run shows what bytes / substrings the coverage feedback discovered as discriminating — useful signals if we ever want a hand-curated corpus. README proof table grows to 8 commands. After this: - 426 unit tests (internal) - 47 conformance harness checks (internal) - 24 secsgem-py interop checks (external — Python ref impl) - 20 secs4j interop checks (external — independent Java impl) - 69 frames dissected by Wireshark HSMS dissector (external) - 196 SEMI E5 KAT assertions (standards body's encoding rules) - **~70k + ~285k random inputs, 0 crashes (external)** - 100k random tool ops with all invariants holding (internal) - YAML validation (internal) - TSan clean on 2 557 assertions (internal correctness aid) Five distinct external proofs now, each covering a different angle. Plan: VERIFICATION.md §4. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
This commit is contained in:
@@ -142,3 +142,46 @@ jobs:
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# that secsgem-py couldn't easily drive.
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- name: secs4j cross-validation
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run: bash interop/secs4j_validate.sh
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libfuzzer:
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runs-on: ubuntu-latest
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container:
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image: ubuntu:24.04
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steps:
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- name: Bootstrap (node + git)
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run: |
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export DEBIAN_FRONTEND=noninteractive
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apt-get update
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apt-get install -y --no-install-recommends \
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git ca-certificates nodejs
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- uses: actions/checkout@v4
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- name: Install clang + libFuzzer runtime
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run: |
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export DEBIAN_FRONTEND=noninteractive
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apt-get install -y --no-install-recommends \
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cmake ninja-build \
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libasio-dev libyaml-cpp-dev \
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python3 python3-yaml \
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clang libclang-rt-18-dev
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- name: Configure (fuzz)
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env:
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CC: clang
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CXX: clang++
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run: cmake -S . -B build-fuzz -G Ninja
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-DCMAKE_BUILD_TYPE=Debug
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-DSECSGEM_FUZZ=ON
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- name: Build fuzz targets
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run: cmake --build build-fuzz --target fuzz_secs2_decode fuzz_sml_parse
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# 60 seconds each — long enough for libFuzzer to explore the
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# decoder/parser without ballooning CI time. Any crash, ASan
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# report, or UBSan flag fails the job.
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- name: Fuzz secs2::decode
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run: build-fuzz/fuzz_secs2_decode -max_total_time=60 -max_len=4096
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- name: Fuzz secs2::try_parse_sml
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run: build-fuzz/fuzz_sml_parse -max_total_time=60 -max_len=4096
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@@ -11,6 +11,27 @@ endif()
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add_compile_options(-Wall -Wextra -Wpedantic)
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# --- libFuzzer (opt-in) ---------------------------------------------------
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# Build with -DSECSGEM_FUZZ=ON to instrument every target with
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# AddressSanitizer + UndefinedBehaviorSanitizer + libFuzzer coverage
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# tracking. Adds two fuzz executables (apps/fuzz_*.cpp) that feed
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# arbitrary input to the SECS-II decoder and the SML parser
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# respectively. CI runs each for ~5 minutes in a dedicated job;
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# customers don't build with this flag.
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#
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# Requires clang (libFuzzer is a clang feature). CMake will switch to
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# clang automatically — invoke with CC=clang CXX=clang++ to be explicit.
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option(SECSGEM_FUZZ "Build libFuzzer harnesses" OFF)
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if(SECSGEM_FUZZ)
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if(NOT CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
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message(FATAL_ERROR "SECSGEM_FUZZ requires clang; re-configure with CXX=clang++")
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endif()
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message(STATUS "libFuzzer enabled — -fsanitize=fuzzer-no-link,address,undefined")
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add_compile_options(-fsanitize=fuzzer-no-link,address,undefined
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-g -O1 -fno-omit-frame-pointer)
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add_link_options(-fsanitize=address,undefined)
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endif()
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# --- ThreadSanitizer (opt-in) ---------------------------------------------
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# Build with -DSECSGEM_TSAN=ON to instrument every target with TSan.
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# Catches data races in EquipmentDataModel access from the io_context
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@@ -104,6 +125,19 @@ target_link_libraries(secs_conformance PRIVATE secsgem)
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add_executable(secs_bench apps/secs_bench.cpp)
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target_link_libraries(secs_bench PRIVATE secsgem)
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if(SECSGEM_FUZZ)
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# libFuzzer entry-point targets. Each owns its own `main` via the
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# `-fsanitize=fuzzer` link flag; do NOT also link them into the
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# regular test binary.
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add_executable(fuzz_secs2_decode apps/fuzz_secs2_decode.cpp)
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target_link_libraries(fuzz_secs2_decode PRIVATE secsgem)
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target_link_options(fuzz_secs2_decode PRIVATE -fsanitize=fuzzer)
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add_executable(fuzz_sml_parse apps/fuzz_sml_parse.cpp)
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target_link_libraries(fuzz_sml_parse PRIVATE secsgem)
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target_link_options(fuzz_sml_parse PRIVATE -fsanitize=fuzzer)
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endif()
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# --- Tests ----------------------------------------------------------------
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enable_testing()
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include(FetchContent)
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@@ -15,6 +15,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
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bash \
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tshark \
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tcpdump \
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clang \
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libclang-rt-18-dev \
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&& rm -rf /var/lib/apt/lists/*
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WORKDIR /app
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@@ -29,6 +29,7 @@ a fresh clone, the codebase implements what
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| 5 | `docker compose run --rm builder /app/build/secs_server --validate-config --config /app/data/equipment.yaml --state-table /app/data/control_state.yaml --pj-state-table /app/data/process_job_state.yaml --cj-state-table /app/data/control_job_state.yaml` | Every shipped YAML config passes structural + referential validation |
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| 6 | `docker compose run --rm builder bash /app/interop/tshark_validate.sh` | **69 HSMS frames** dissected by Wireshark's HSMS dissector (independent third codec) with no malformed packets |
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| 7 | `bash interop/secs4j_validate.sh` | **20 cross-validation checks** PASS against [secs4java8](https://github.com/kenta-shimizu/secs4java8) (independent Java implementation), covering full GEM 300 body shapes (S3, S14, S16) plus S2F49 / S5F13 / S2F23 |
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| 8 | `cmake -B build-fuzz -DSECSGEM_FUZZ=ON && build-fuzz/fuzz_secs2_decode -max_total_time=60` | **~70 000 random inputs** through `secs2::decode`, **~285 000** through `try_parse_sml`, ASan + UBSan + libFuzzer coverage, **0 crashes** |
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Plus, on every push to `main`, [Gitea Actions](.gitea/workflows/ci.yml)
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runs both a **Release build + full test suite** and a separate
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@@ -0,0 +1,32 @@
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// libFuzzer harness for the SECS-II decoder.
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//
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// Feed arbitrary bytes to secs2::decode and assert no crash, no
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// UB, no ASan-flagged memory error. Coverage-guided fuzzing
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// explores edges that hand-written tests can't predict.
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//
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// Build: cmake -S . -B build-fuzz -G Ninja -DSECSGEM_FUZZ=ON
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// Run: build-fuzz/fuzz_secs2_decode -max_total_time=300 -max_len=65536
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#include <cstdint>
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#include <cstddef>
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#include <vector>
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#include "secsgem/secs2/codec.hpp"
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extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
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// The decoder is expected to throw secs2::CodecError on malformed
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// input — that's the contract. Any other exception type, or a
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// segfault / ASan flag, is a bug.
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try {
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std::vector<uint8_t> bytes(data, data + size);
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auto item = secsgem::secs2::decode(bytes);
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(void)item;
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} catch (const secsgem::secs2::CodecError&) {
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// expected: well-defined failure path
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} catch (...) {
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// anything else escaping is a hardening bug — crash so libFuzzer
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// captures the input.
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__builtin_trap();
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}
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return 0;
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}
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@@ -0,0 +1,22 @@
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// libFuzzer harness for the SML parser. try_parse_sml returns
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// std::nullopt on a malformed input rather than throwing, so any
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// exception leaking is a bug.
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#include <cstdint>
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#include <cstddef>
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#include <string>
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#include "secsgem/secs2/sml.hpp"
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extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
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std::string s(reinterpret_cast<const char*>(data), size);
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try {
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auto item = secsgem::secs2::try_parse_sml(s);
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(void)item;
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} catch (...) {
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// try_parse_sml is contractually noexcept-equivalent — must
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// return nullopt, never throw. Anything escaping is a bug.
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__builtin_trap();
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}
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return 0;
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}
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