[2/2] ci: build and run minimal fuzzers in GitHub CI

Commit Message

Josh Steadmon Jan. 19, 2024, 9:38 p.m. UTC

To prevent bitrot, we would like to regularly exercise the fuzz tests in
order to make sure they still link & run properly. We already compile
the fuzz test objects as part of the default `make` target, but we do
not link the executables due to the fuzz tests needing specific
compilers and compiler features. This has lead to frequent build
breakages for the fuzz tests.

To remedy this, we can add a CI step to actually link the fuzz
executables, and run them (with finite input rather than the default
infinite random input mode) to verify that they execute properly.

Since the main use of the fuzz tests is via OSS-Fuzz [1], and OSS-Fuzz
only runs tests on Linux [2], we only set up a CI test for the fuzzers
on Linux.

[1] https://github.com/google/oss-fuzz
[2] https://google.github.io/oss-fuzz/further-reading/fuzzer-environment/

Signed-off-by: Josh Steadmon <[e-mail]>
---
 .github/workflows/main.yml          | 11 +++++++++++
 Makefile                            |  3 +++
 ci/run-build-and-minimal-fuzzers.sh | 19 +++++++++++++++++++
 3 files changed, 33 insertions(+)
 create mode 100755 ci/run-build-and-minimal-fuzzers.sh

Patch

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 9fdbd54028..4d97da57ec 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -309,6 +309,17 @@  jobs:
       with:
         name: failed-tests-${{matrix.vector.jobname}}
         path: ${{env.FAILED_TEST_ARTIFACTS}}
+  fuzz-smoke-test:
+    name: fuzz smoke test
+    needs: ci-config
+    if: needs.ci-config.outputs.enabled == 'yes'
+    env:
+      CC: clang
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - run: ci/install-dependencies.sh
+    - run: ci/run-build-and-minimal-fuzzers.sh
   dockerized:
     name: ${{matrix.vector.jobname}} (${{matrix.vector.image}})
     needs: ci-config
diff --git a/Makefile b/Makefile
index 1e9bd6430f..2e94c566e0 100644
--- a/Makefile
+++ b/Makefile
@@ -752,6 +752,9 @@  SCRIPTS = $(SCRIPT_SH_GEN) \
 
 ETAGS_TARGET = TAGS
 
+# If you add a new fuzzer, please also make sure to run it in
+# ci/run-build-and-minimal-fuzzers.sh so that we make sure it still links and
+# runs in the future.
 FUZZ_OBJS += oss-fuzz/dummy-cmd-main.o
 FUZZ_OBJS += oss-fuzz/fuzz-commit-graph.o
 FUZZ_OBJS += oss-fuzz/fuzz-date.o
diff --git a/ci/run-build-and-minimal-fuzzers.sh b/ci/run-build-and-minimal-fuzzers.sh
new file mode 100755
index 0000000000..8ba486f659
--- /dev/null
+++ b/ci/run-build-and-minimal-fuzzers.sh
@@ -0,0 +1,19 @@ 
+#!/bin/sh
+#
+# Build and test Git's fuzzers
+#
+
+. ${0%/*}/lib.sh
+
+group "Build fuzzers" make \
+	CC=clang \
+	CXX=clang++ \
+	CFLAGS="-fsanitize=fuzzer-no-link,address" \
+	LIB_FUZZING_ENGINE="-fsanitize=fuzzer,address" \
+	fuzz-all
+
+for fuzzer in commit-graph date pack-headers pack-idx ; do
+	begin_group "fuzz-$fuzzer"
+	./oss-fuzz/fuzz-$fuzzer -verbosity=0 -runs=1 || exit 1
+	end_group "fuzz-$fuzzer"
+done