Add support for fuzz testing using libFuzzer

.github/workflows/tests.yml

@@ -298,9 +298,54 @@ jobs:
         name: Build WASM package with wasm-pack
         run: wasm-pack build --target web --no-default-features --features alloc,panic-handler
 
+  fuzz-test:
+    name: Fuzz Testing
+    needs: check-previous-run
+    if: needs.check-previous-run.outputs.should_skip != 'true'
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-24.04, ubuntu-24.04-arm]
+        fuzz-target:
+          - digest_crc32_autosar
+          - digest_crc32_bzip2
+          - digest_crc32_iscsi
+          - digest_crc32_iso_hdlc
+          - digest_crc64_ecma_182
+          - digest_crc64_nvme
+          - checksum_crc32_autosar
+          - checksum_crc32_bzip2
+          - checksum_crc32_iscsi
+          - checksum_crc32_iso_hdlc
+          - checksum_crc64_ecma_182
+          - checksum_crc64_nvme
+    steps:
+      - uses: actions/checkout@v4 # not pinning to commit hash since this is a GitHub action, which we trust
+      - uses: actions-rust-lang/setup-rust-toolchain@9d7e65c320fdb52dcd45ffaa68deb6c02c8754d9 # v1.12.0
+        with:
+          toolchain: nightly
+          cache-key: ${{ matrix.os }}-nightly-fuzz
+      - name: Install cargo-fuzz
+        run: cargo install cargo-fuzz
+      - name: Run fuzzer
+        run: |
+          cargo fuzz run ${{ matrix.fuzz-target }} -- \
+            -max_total_time=60 \
+            -rss_limit_mb=2048 \
+            -timeout=10 \
+            -print_final_stats=1
+        continue-on-error: true
+      - name: Upload artifacts on crash
+        if: failure()
+        uses: actions/upload-artifact@v4
+        with:
+          name: fuzz-artifacts-${{ matrix.os }}-${{ matrix.fuzz-target }}
+          path: fuzz/artifacts/${{ matrix.fuzz-target }}/
+
   tests-complete:
     name: All tests complete
-    needs: [check-previous-run, test-aarch64, test-x86_64, test-x86-linux, test-x86-windows, test-software, miri-test-x86_64, test-no-std, test-wasm]
+    needs: [check-previous-run, test-aarch64, test-x86_64, test-x86-linux, test-x86-windows, test-software, miri-test-x86_64, test-no-std, test-wasm, fuzz-test]
     if: always()
     runs-on: ubuntu-latest
     steps:
@@ -323,7 +368,8 @@ jobs:
              [ "${{ needs.test-software.result }}" == "failure" ] || \
              [ "${{ needs.miri-test-x86_64.result }}" == "failure" ] || \
              [ "${{ needs.test-no-std.result }}" == "failure" ] || \
-             [ "${{ needs.test-wasm.result }}" == "failure" ]; then
+             [ "${{ needs.test-wasm.result }}" == "failure" ] || \
+             [ "${{ needs.fuzz-test.result }}" == "failure" ]; then
             echo "✗ One or more test jobs failed"
             exit 1
           fi

README.md

@@ -474,6 +474,12 @@ In theory, much of the "heavy lifting" has been done, so it should be possible t
 
 PRs welcome!
 
+## Memory Safety
+
+Given the heavy use of hardware intrinsics, this crate uses a decent amount of `unsafe` code.
+
+To help ensure memory safety, this crate is validated using [Miri](https://github.com/rust-lang/miri) on `x86_64` as well as fuzz tested using [libFuzzer](https://github.com/rust-fuzz/libfuzzer) over millions of iterations.
+
 ## References
 
 * [Catalogue of parametrised CRC algorithms](https://reveng.sourceforge.io/crc-catalogue/all.htm)

fuzz/.gitignore

@@ -0,0 +1,4 @@
+target
+corpus
+artifacts
+coverage

fuzz/Cargo.toml

@@ -0,0 +1,98 @@
+[package]
+name = "crc-fast-rust-fuzz"
+version = "0.1.0"
+publish = false
+edition = "2021"
+
+[package.metadata]
+cargo-fuzz = true
+
+[dependencies]
+libfuzzer-sys = "0.4"
+
+[dependencies.crc-fast]
+path = ".."
+
+[[bin]]
+name = "digest_crc32_autosar"
+path = "fuzz_targets/digest_crc32_autosar.rs"
+test = false
+doc = false
+bench = false
+
+[[bin]]
+name = "digest_crc32_bzip2"
+path = "fuzz_targets/digest_crc32_bzip2.rs"
+test = false
+doc = false
+bench = false
+
+[[bin]]
+name = "digest_crc32_iscsi"
+path = "fuzz_targets/digest_crc32_iscsi.rs"
+test = false
+doc = false
+bench = false
+
+[[bin]]
+name = "digest_crc32_iso_hdlc"
+path = "fuzz_targets/digest_crc32_iso_hdlc.rs"
+test = false
+doc = false
+bench = false
+
+[[bin]]
+name = "digest_crc64_ecma_182"
+path = "fuzz_targets/digest_crc64_ecma_182.rs"
+test = false
+doc = false
+bench = false
+
+[[bin]]
+name = "digest_crc64_nvme"
+path = "fuzz_targets/digest_crc64_nvme.rs"
+test = false
+doc = false
+bench = false
+
+[[bin]]
+name = "checksum_crc32_autosar"
+path = "fuzz_targets/checksum_crc32_autosar.rs"
+test = false
+doc = false
+bench = false
+
+[[bin]]
+name = "checksum_crc32_bzip2"
+path = "fuzz_targets/checksum_crc32_bzip2.rs"
+test = false
+doc = false
+bench = false
+
+[[bin]]
+name = "checksum_crc32_iscsi"
+path = "fuzz_targets/checksum_crc32_iscsi.rs"
+test = false
+doc = false
+bench = false
+
+[[bin]]
+name = "checksum_crc32_iso_hdlc"
+path = "fuzz_targets/checksum_crc32_iso_hdlc.rs"
+test = false
+doc = false
+bench = false
+
+[[bin]]
+name = "checksum_crc64_ecma_182"
+path = "fuzz_targets/checksum_crc64_ecma_182.rs"
+test = false
+doc = false
+bench = false
+
+[[bin]]
+name = "checksum_crc64_nvme"
+path = "fuzz_targets/checksum_crc64_nvme.rs"
+test = false
+doc = false
+bench = false

fuzz/fuzz_targets/checksum_crc32_autosar.rs

@@ -0,0 +1,10 @@
+//! Fuzz target for CRC-32/AUTOSAR checksum calculation, which is a reflected variant.
+
+#![no_main]
+
+use crc_fast::{CrcAlgorithm, checksum};
+use libfuzzer_sys::fuzz_target;
+
+fuzz_target!(|data: &[u8]| {
+    checksum(CrcAlgorithm::Crc32Autosar, data);
+});

fuzz/fuzz_targets/checksum_crc32_bzip2.rs

@@ -0,0 +1,10 @@
+//! Fuzz target for CRC-32/BZIP2 checksum calculation, which is a forward variant.
+
+#![no_main]
+
+use crc_fast::{CrcAlgorithm, checksum};
+use libfuzzer_sys::fuzz_target;
+
+fuzz_target!(|data: &[u8]| {
+    checksum(CrcAlgorithm::Crc32Bzip2, data);
+});