[core] Add a fuzzing regression test github action

While fuzzing subzero core before the nanopb 0.4.5 upgrade,
the fuzzer found a bunch of inputs which triggered UBSAN.

This PR creates a regression test that runs the fuzzer with these inputs
and verifies that none of them fail now that we're on nanopb 0.4.5.

If more bad inputs are discovered later, they can be added to this directory
after the corresponding bugs are fixed.

.github/workflows/fuzzing-regression-test.yml

@@ -0,0 +1,64 @@
+# Subzero regression test for bugs discovered with fuzz testing
+name: "Fuzzing Regression Test"
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    # The branches below must be a subset of the branches above
+    branches: [master]
+  schedule:
+    # Daily at 1am
+    - cron: '0 1 * * *'
+
+jobs:
+  fuzzing-regression-test:
+    name: "Fuzzing Regression Test"
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        shell: bash -euxo pipefail {0}
+
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version: [3.9]
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+      with:
+        # We must fetch at least the immediate parents so that if this is
+        # a pull request then we can checkout the head.
+        fetch-depth: 2
+        submodules: 'recursive'
+
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python-version }}
+
+    - name: Display Python version
+      run: |
+        python -c "import sys; print(sys.version)"
+
+    - name: Install dependencies
+      run: scripts/ubuntu_install_protobuf.sh
+
+    - name: Setup Clang
+      uses: egor-tensin/[email protected]
+      with:
+        version: latest
+        platform: x64
+
+    # Build CORE with ASAN, UBSAN, and libfuzzer
+    - name: Build Subzero Core (ASAN+UBSAN+FUZZER)
+      run: |
+        export CC=`which clang`
+        export CXX=`which clang++`
+        scripts/build_core.sh -DENABLE_ASAN=ON -DENABLE_UBSAN=ON -DENABLE_FUZZER=ON
+
+    - name: Run Subzero CORE Fuzzing regression test
+      run: |
+        cd ${{ github.workspace }}
+        ./core/build/subzero_fuzzer-testnet ./core/fuzzing_regression_test_inputs/*

scripts/build_core.sh

@@ -8,9 +8,19 @@ cd core/build
 # For mainnet. Skip compile_db generation
 TARGET=dev CURRENCY=btc-mainnet cmake ../ "$@"
 make
-mv subzero subzero-mainnet
+if [ -f subzero ]; then
+  mv subzero subzero-mainnet
+fi
+if [ -f subzero_fuzzer ]; then
+  mv subzero_fuzzer subzero_fuzzer-mainnet
+fi
 # For testnet. Generate compile_db for clang static analyzer
 make clean
 TARGET=dev CURRENCY=btc-testnet cmake ../ -DCMAKE_EXPORT_COMPILE_COMMANDS=ON "$@"
 make
-mv subzero subzero-testnet
+if [ -f subzero ]; then
+  mv subzero subzero-testnet
+fi
+if [ -f subzero_fuzzer ]; then
+  mv subzero_fuzzer subzero_fuzzer-testnet
+fi