Afl

.github/workflows/release.yaml

@@ -28,6 +28,11 @@ jobs:
         with:
           node-version: 22
           cache: "npm"
+      - name: rust
+        uses: dtolnay/rust-toolchain@stable
+      - name: rust target (macos x64)
+        if: ${{ matrix.os == 'macos-latest' && matrix.arch == '--arch x86_64' }}
+        run: rustup target add x86_64-apple-darwin
       - name: MSVC (windows)
         uses: ilammy/msvc-dev-cmd@v1
         if: contains(matrix.os, 'windows')

.github/workflows/run-all-tests-main.yaml

@@ -21,18 +21,25 @@ jobs:
           path: |
             packages/fuzzer/prebuilds
           key:
-            fuzzer-cache-${{ runner.os }}-${{
-            hashFiles('packages/fuzzer/CMakeLists.txt',
-            'packages/fuzzer/**/*.h', 'packages/fuzzer/**/*.cpp') }}
+            fuzzer-cache-${{ runner.os }}-${{ hashFiles('package-lock.json',
+            'package.json', 'packages/fuzzer/package.json',
+            'packages/fuzzer/CMakeLists.txt', 'packages/fuzzer/**/*.h',
+            'packages/fuzzer/**/*.cpp', 'packages/fuzzer/rust/Cargo.toml',
+            'packages/fuzzer/rust/Cargo.lock',
+            'packages/fuzzer/rust/src/**/*.rs') }}
       - name: node
         uses: actions/setup-node@v6
         with:
           node-version: 22
           cache: "npm"
+      - name: rust
+        uses: dtolnay/rust-toolchain@stable
       - name: install dependencies
         run: npm ci
       - name: build project
         run: npm run build
+      - name: test LibAFL runtime
+        run: cargo test --manifest-path packages/fuzzer/rust/Cargo.toml
       - name: build fuzzer
         if: ${{ steps.cache-fuzzer.outputs.cache-hit != 'true' }}
         run: npm run build --workspace=@jazzer.js/fuzzer

.github/workflows/run-all-tests-pr.yaml

@@ -24,13 +24,17 @@ jobs:
         with:
           node-version: 22
           cache: "npm"
+      - name: rust
+        uses: dtolnay/rust-toolchain@stable
       - name: install dependencies
         run: npm ci
       - name: install clang-tidy
         run: sudo apt-get install -y clang-tidy
       - name: build project
         # Build project so that imports can be checked during linting
         run: npm run build
+      - name: test LibAFL runtime
+        run: cargo test --manifest-path packages/fuzzer/rust/Cargo.toml
       - name: build fuzzer
         # Build the native addon so that CMake downloads libFuzzer and
         # generates compile_commands.json, which are needed by clang-tidy
@@ -59,14 +63,19 @@ jobs:
           path: |
             packages/fuzzer/prebuilds
           key:
-            fuzzer-cache-${{ matrix.os }}-${{
-            hashFiles('packages/fuzzer/CMakeLists.txt',
-            'packages/fuzzer/**/*.h', 'packages/fuzzer/**/*.cpp') }}
+            fuzzer-cache-${{ matrix.os }}-${{ hashFiles('package-lock.json',
+            'package.json', 'packages/fuzzer/package.json',
+            'packages/fuzzer/CMakeLists.txt', 'packages/fuzzer/**/*.h',
+            'packages/fuzzer/**/*.cpp', 'packages/fuzzer/rust/Cargo.toml',
+            'packages/fuzzer/rust/Cargo.lock',
+            'packages/fuzzer/rust/src/**/*.rs') }}
       - name: node
         uses: actions/setup-node@v6
         with:
           node-version: ${{ matrix.node }}
           cache: "npm"
+      - name: rust
+        uses: dtolnay/rust-toolchain@stable
       - name: MSVC (windows)
         uses: ilammy/msvc-dev-cmd@v1
         if: contains(matrix.os, 'windows')
@@ -95,6 +104,8 @@ jobs:
         with:
           node-version: 22
           cache: "npm"
+      - name: rust
+        uses: dtolnay/rust-toolchain@stable
       - name: MSVC (windows)
         uses: ilammy/msvc-dev-cmd@v1
         if: contains(matrix.os, 'windows')

.prettierignore

@@ -6,3 +6,4 @@ node_modules
 .idea
 .vscode
 compile_commands.json
+packages/fuzzer/rust/target

README.md

@@ -17,8 +17,9 @@
 
 Jazzer.js is a coverage-guided, in-process fuzzer for the
 [Node.js](https://nodejs.org) platform developed by
-[Code Intelligence](https://www.code-intelligence.com). It is based on
-[libFuzzer](https://llvm.org/docs/LibFuzzer.html) and brings many of its
+[Code Intelligence](https://www.code-intelligence.com). It supports
+[libFuzzer](https://llvm.org/docs/LibFuzzer.html) and
+[LibAFL](https://github.com/AFLplusplus/LibAFL) backends and brings
 instrumentation-powered mutation features to the JavaScript ecosystem.
 
 ## Quickstart
@@ -47,6 +48,9 @@ To use Jazzer.js in your own project follow these few simple steps:
    npx jazzer FuzzTarget
    ```
 
+   CLI fuzzing uses the LibAFL backend by default. To run with libFuzzer
+   instead, add `--engine=libfuzzer`.
+
 4. Enjoy fuzzing!
 
 ## Usage

benchmarks/engine_smoke/.gitignore

@@ -0,0 +1,3 @@
+node_modules/
+package-lock.json
+work/

benchmarks/engine_smoke/anomaly.js

@@ -0,0 +1,189 @@
+/*
+ * Copyright 2026 Code Intelligence GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+const { spawnSync } = require("child_process");
+const fs = require("fs");
+const path = require("path");
+
+const benchmarkDirectory = __dirname;
+const workDirectory = path.join(benchmarkDirectory, "work", "anomalies");
+const engineTarget = path.join(
+	benchmarkDirectory,
+	"..",
+	"..",
+	"tests",
+	"engine",
+	"fuzz.js",
+);
+const asyncTarget = path.join(benchmarkDirectory, "anomaly_fuzz.js");
+
+function removeIfExists(targetPath) {
+	fs.rmSync(targetPath, { force: true, recursive: true });
+}
+
+function ensureDirectory(targetPath) {
+	fs.mkdirSync(targetPath, { recursive: true });
+}
+
+function runCommand(label, args, cwd, outputDirectory, expectedStatus = 0) {
+	console.log(`\n[anomaly] ${label}`);
+	console.log(`[anomaly] command: npx ${args.join(" ")}`);
+	ensureDirectory(outputDirectory);
+	const sanitizedLabel = label.replace(/[^a-z0-9]+/gi, "-").toLowerCase();
+	const stdoutPath = path.join(outputDirectory, `${sanitizedLabel}.stdout.log`);
+	const stderrPath = path.join(outputDirectory, `${sanitizedLabel}.stderr.log`);
+	const stdoutFd = fs.openSync(stdoutPath, "w");
+	const stderrFd = fs.openSync(stderrPath, "w");
+	const startedAt = Date.now();
+	const proc = spawnSync("npx", args, {
+		cwd,
+		env: { ...process.env },
+		shell: true,
+		stdio: ["ignore", stdoutFd, stderrFd],
+		windowsHide: true,
+	});
+	const elapsedMs = Date.now() - startedAt;
+	fs.closeSync(stdoutFd);
+	fs.closeSync(stderrFd);
+
+	if (proc.status !== expectedStatus) {
+		throw new Error(
+			`${label} failed with exit code ${proc.status}\nSTDOUT (${stdoutPath}):\n${fs.readFileSync(stdoutPath, "utf8")}\nSTDERR (${stderrPath}):\n${fs.readFileSync(stderrPath, "utf8")}`,
+		);
+	}
+
+	return {
+		elapsedMs,
+		stderrPath,
+		stdoutPath,
+	};
+}
+
+function parseExecsPerSecond(stderrPath) {
+	const stderr = fs.readFileSync(stderrPath, "utf8");
+	const match = stderr.match(/speed:\s+([0-9.]+) exec\/s/);
+	if (!match) {
+		throw new Error(`No LibAFL done line found in ${stderrPath}`);
+	}
+	return Number.parseFloat(match[1]);
+}
+
+function runGuidedNumericSmoke() {
+	const outputDirectory = path.join(workDirectory, "guided-numeric");
+	const corpusDirectory = path.join(outputDirectory, "corpus");
+	removeIfExists(outputDirectory);
+	ensureDirectory(corpusDirectory);
+	fs.writeFileSync(path.join(corpusDirectory, "seed"), Buffer.alloc(4));
+
+	const result = runCommand(
+		"guided numeric solve",
+		[
+			"jazzer",
+			engineTarget,
+			"-f",
+			"guided_numeric",
+			"--engine=afl",
+			"--sync",
+			"--disable_bug_detectors=.*",
+			"--",
+			corpusDirectory,
+			"-runs=4000",
+			"-seed=1337",
+			"-max_len=16",
+			`-artifact_prefix=${outputDirectory}${path.sep}`,
+		],
+		benchmarkDirectory,
+		outputDirectory,
+		77,
+	);
+
+	const output =
+		fs.readFileSync(result.stdoutPath, "utf8") +
+		fs.readFileSync(result.stderrPath, "utf8");
+	if (!output.includes("AFL numeric guidance finding")) {
+		throw new Error("Guided numeric smoke did not report the expected finding");
+	}
+
+	return {
+		name: "guided-numeric",
+		elapsedMs: result.elapsedMs,
+	};
+}
+
+function runAsyncSmoke() {
+	const outputDirectory = path.join(workDirectory, "async-smoke");
+	const corpusDirectory = path.join(outputDirectory, "corpus");
+	removeIfExists(outputDirectory);
+	ensureDirectory(corpusDirectory);
+	fs.writeFileSync(path.join(corpusDirectory, "seed"), "async-seed");
+
+	const result = runCommand(
+		"async throughput smoke",
+		[
+			"jazzer",
+			asyncTarget,
+			"-f",
+			"async_smoke",
+			"--engine=afl",
+			"--disable_bug_detectors=.*",
+			"--",
+			corpusDirectory,
+			"-runs=2000",
+			"-seed=9001",
+			"-max_len=128",
+			`-artifact_prefix=${outputDirectory}${path.sep}`,
+		],
+		benchmarkDirectory,
+		outputDirectory,
+	);
+
+	const execsPerSecond = parseExecsPerSecond(result.stderrPath);
+	if (execsPerSecond <= 0) {
+		throw new Error("Async smoke reported a non-positive exec/sec rate");
+	}
+	if (result.elapsedMs > 30000) {
+		throw new Error(
+			`Async smoke took unexpectedly long: ${result.elapsedMs} ms`,
+		);
+	}
+
+	return {
+		name: "async-smoke",
+		elapsedMs: result.elapsedMs,
+		execsPerSecond,
+	};
+}
+
+function main() {
+	ensureDirectory(workDirectory);
+	const results = [runGuidedNumericSmoke(), runAsyncSmoke()];
+	for (const result of results) {
+		const stats = [`elapsed_ms=${result.elapsedMs}`];
+		if (result.execsPerSecond !== undefined) {
+			stats.push(`execs_per_second=${result.execsPerSecond}`);
+		}
+		console.log(`[anomaly] ${result.name}: ${stats.join(" ")}`);
+	}
+	fs.writeFileSync(
+		path.join(workDirectory, "results.json"),
+		JSON.stringify(results, null, 2),
+	);
+	console.log(
+		`\n[anomaly] wrote machine-readable results to ${path.join(workDirectory, "results.json")}`,
+	);
+}
+
+main();

benchmarks/engine_smoke/anomaly_fuzz.js

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2026 Code Intelligence GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+module.exports.async_smoke = function (data) {
+	let checksum = 0;
+	for (const byte of data) {
+		checksum = ((checksum * 33) ^ byte) & 0xffff;
+	}
+
+	return new Promise((resolve) => {
+		setImmediate(() => {
+			if (checksum === 0x1337) {
+				// Exercise an extra branch without turning this into a finding target.
+				checksum ^= data.length;
+			}
+			resolve(checksum);
+		});
+	});
+};