Lagom/Fuzzers: Add Fuzzilli version of FuzzJs

Fuzzilli is a JavaScript engine fuzzer made by googleprojectzero.

https://github.com/googleprojectzero/fuzzilli/

Meta/Lagom/Fuzzers/CMakeLists.txt

@@ -25,6 +25,15 @@ target_link_libraries(FuzzJs
     PRIVATE $<$<C_COMPILER_ID:Clang>:-fsanitize=fuzzer>
     )
 
+add_executable(FuzzilliJs FuzzilliJs.cpp)
+target_compile_options(FuzzilliJs
+    PRIVATE $<$<C_COMPILER_ID:Clang>:-g -O1 -fsanitize-coverage=trace-pc-guard>
+    )
+target_link_libraries(FuzzilliJs
+    PUBLIC Lagom
+    PRIVATE $<$<C_COMPILER_ID:Clang>:-fsanitize-coverage=trace-pc-guard>
+    )
+
 add_executable(FuzzMarkdown FuzzMarkdown.cpp)
 target_compile_options(FuzzMarkdown
     PRIVATE $<$<C_COMPILER_ID:Clang>:-g -O1 -fsanitize=fuzzer>

Meta/Lagom/Fuzzers/FuzzilliJs.cpp

@@ -0,0 +1,258 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <AK/Function.h>
+#include <AK/String.h>
+#include <AK/StringView.h>
+#include <LibJS/Forward.h>
+#include <LibJS/Interpreter.h>
+#include <LibJS/Lexer.h>
+#include <LibJS/Parser.h>
+#include <LibJS/Runtime/GlobalObject.h>
+#include <signal.h>
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <string>
+#include <sys/mman.h>
+
+#include <sys/stat.h>
+
+//
+// BEGIN FUZZING CODE
+//
+
+#define REPRL_CRFD 100
+#define REPRL_CWFD 101
+#define REPRL_DRFD 102
+#define REPRL_DWFD 103
+#define REPRL_MAX_DATA_SIZE (16 * 1024 * 1024)
+
+#define SHM_SIZE 0x100000
+#define MAX_EDGES ((SHM_SIZE - 4) * 8)
+
+#define CHECK(cond)                                \
+    if (!(cond)) {                                 \
+        fprintf(stderr, "\"" #cond "\" failed\n"); \
+        _exit(-1);                                 \
+    }
+
+struct shmem_data {
+    uint32_t num_edges;
+    unsigned char edges[];
+};
+
+struct shmem_data* __shmem;
+uint32_t *__edges_start, *__edges_stop;
+
+void __sanitizer_cov_reset_edgeguards()
+{
+    uint64_t N = 0;
+    for (uint32_t* x = __edges_start; x < __edges_stop && N < MAX_EDGES; x++)
+        *x = ++N;
+}
+
+extern "C" void __sanitizer_cov_trace_pc_guard_init(uint32_t* start, uint32_t* stop)
+{
+    // Avoid duplicate initialization
+    if (start == stop || *start)
+        return;
+
+    if (__edges_start != NULL || __edges_stop != NULL) {
+        fprintf(stderr, "Coverage instrumentation is only supported for a single module\n");
+        _exit(-1);
+    }
+
+    __edges_start = start;
+    __edges_stop = stop;
+
+    // Map the shared memory region
+    const char* shm_key = getenv("SHM_ID");
+    if (!shm_key) {
+        puts("[COV] no shared memory bitmap available, skipping");
+        __shmem = (struct shmem_data*)malloc(SHM_SIZE);
+    } else {
+        int fd = shm_open(shm_key, O_RDWR, S_IREAD | S_IWRITE);
+        if (fd <= -1) {
+            fprintf(stderr, "Failed to open shared memory region: %s\n", strerror(errno));
+            _exit(-1);
+        }
+
+        __shmem = (struct shmem_data*)mmap(0, SHM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+        if (__shmem == MAP_FAILED) {
+            fprintf(stderr, "Failed to mmap shared memory region\n");
+            _exit(-1);
+        }
+    }
+
+    __sanitizer_cov_reset_edgeguards();
+
+    __shmem->num_edges = stop - start;
+    printf("[COV] edge counters initialized. Shared memory: %s with %u edges\n", shm_key, __shmem->num_edges);
+}
+
+extern "C" void __sanitizer_cov_trace_pc_guard(uint32_t* guard)
+{
+    // There's a small race condition here: if this function executes in two threads for the same
+    // edge at the same time, the first thread might disable the edge (by setting the guard to zero)
+    // before the second thread fetches the guard value (and thus the index). However, our
+    // instrumentation ignores the first edge (see libcoverage.c) and so the race is unproblematic.
+    uint32_t index = *guard;
+    // If this function is called before coverage instrumentation is properly initialized we want to return early.
+    if (!index)
+        return;
+    __shmem->edges[index / 8] |= 1 << (index % 8);
+    *guard = 0;
+}
+
+//
+// END FUZZING CODE
+//
+
+class TestRunnerGlobalObject : public JS::GlobalObject {
+public:
+    TestRunnerGlobalObject();
+    virtual ~TestRunnerGlobalObject() override;
+
+    virtual void initialize() override;
+
+private:
+    virtual const char* class_name() const override { return "TestRunnerGlobalObject"; }
+
+    JS_DECLARE_NATIVE_FUNCTION(fuzzilli);
+};
+
+TestRunnerGlobalObject::TestRunnerGlobalObject()
+{
+}
+
+TestRunnerGlobalObject::~TestRunnerGlobalObject()
+{
+}
+
+JS_DEFINE_NATIVE_FUNCTION(TestRunnerGlobalObject::fuzzilli)
+{
+    if (!vm.argument_count())
+        return JS::js_undefined();
+
+    auto operation = vm.argument(0).to_string(global_object);
+    if (vm.exception())
+        return {};
+
+    if (operation == "FUZZILLI_CRASH") {
+        auto type = vm.argument(1).to_i32(global_object);
+        if (vm.exception())
+            return {};
+        switch (type) {
+        case 0:
+            *((int*)0x41414141) = 0x1337;
+            break;
+        default:
+            ASSERT_NOT_REACHED();
+            break;
+        }
+    } else if (operation == "FUZZILLI_PRINT") {
+        static FILE* fzliout = fdopen(REPRL_DWFD, "w");
+        if (!fzliout) {
+            dbg() << "Fuzzer output not available";
+            fzliout = stdout;
+        }
+
+        auto string = vm.argument(1).to_string(global_object);
+        if (vm.exception())
+            return {};
+        fprintf(fzliout, "%s\n", string.characters());
+        fflush(fzliout);
+    }
+
+    return JS::js_undefined();
+}
+
+void TestRunnerGlobalObject::initialize()
+{
+    JS::GlobalObject::initialize();
+    define_property("global", this, JS::Attribute::Enumerable);
+    define_native_function("fuzzilli", fuzzilli, 2);
+}
+
+int main(int, char**)
+{
+    char* reprl_input = nullptr;
+
+    char helo[] = "HELO";
+    if (write(REPRL_CWFD, helo, 4) != 4 || read(REPRL_CRFD, helo, 4) != 4) {
+        ASSERT_NOT_REACHED();
+    }
+
+    ASSERT(memcmp(helo, "HELO", 4) == 0);
+    reprl_input = (char*)mmap(0, REPRL_MAX_DATA_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, REPRL_DRFD, 0);
+    ASSERT(reprl_input != MAP_FAILED);
+
+    auto vm = JS::VM::create();
+    auto interpreter = JS::Interpreter::create<TestRunnerGlobalObject>(*vm);
+
+    while (true) {
+        unsigned action;
+        ASSERT(read(REPRL_CRFD, &action, 4) == 4);
+        ASSERT(action == 'cexe');
+
+        size_t script_size;
+        ASSERT(read(REPRL_CRFD, &script_size, 8) == 8);
+        ASSERT(script_size < REPRL_MAX_DATA_SIZE);
+        ByteBuffer data_buffer;
+        if (data_buffer.size() < script_size)
+            data_buffer.grow(script_size - data_buffer.size());
+        ASSERT(data_buffer.size() >= script_size);
+        memcpy(data_buffer.data(), reprl_input, script_size);
+
+        int result = 0;
+
+        auto js = AK::StringView(static_cast<const unsigned char*>(data_buffer.data()), script_size);
+
+        auto lexer = JS::Lexer(js);
+        auto parser = JS::Parser(lexer);
+        auto program = parser.parse_program();
+        if (parser.has_errors()) {
+            result = 1;
+        } else {
+            interpreter->run(interpreter->global_object(), *program);
+            if (interpreter->exception()) {
+                result = 1;
+                vm->clear_exception();
+            }
+        }
+
+        fflush(stdout);
+        fflush(stderr);
+
+        int status = (result & 0xff) << 8;
+        ASSERT(write(REPRL_CWFD, &status, 4) == 4);
+        __sanitizer_cov_reset_edgeguards();
+    }
+
+    return 0;
+}

Meta/Lagom/Fuzzers/FuzzilliJsInstructions.md

@@ -0,0 +1,8 @@
+# How to use FuzzilliJs
+
+1. Download a copy of the Fuzzilli repo from https://github.com/googleprojectzero/fuzzilli
+2. Install Swift and make sure it's in your path environment variable.
+3. Build FuzzilliJs as you would the other fuzzers. [See README.md in the parent folder.](https://github.com/SerenityOS/serenity/blob/master/Meta/Lagom/ReadMe.md)
+4. Apply the add-serenity-support-to-fuzzilli.patch patch file to the Fuzzilli root directory. ```patch -p1 < /path/to/add-serenity-support-to-fuzzilli.patch```
+5. Build Fuzzilli with ```swift build -c release```
+6. Run Fuzzilli with ```swift run -c release FuzzilliCli --profile=serenity /path/to/FuzzilliJs```. See ```swift run FuzzilliCli --help``` for options.

Meta/Lagom/Fuzzers/add-serenity-support-to-fuzzilli.patch

@@ -0,0 +1,44 @@
+diff --git a/Sources/FuzzilliCli/Profiles/Profile.swift b/Sources/FuzzilliCli/Profiles/Profile.swift
+index 6d8a795..a506d41 100644
+--- a/Sources/FuzzilliCli/Profiles/Profile.swift
++++ b/Sources/FuzzilliCli/Profiles/Profile.swift
+@@ -32,6 +32,33 @@ struct Profile {
+     let additionalBuiltins: [String: Type]
+ }
+ 
++let serenityProfile = Profile(
++    processArguments: [""],
++
++    processEnv: ["UBSAN_OPTIONS":"handle_segv=0 handle_abrt=0"],
++
++    codePrefix: """
++                function main() {
++                """,
++
++    codeSuffix: """
++                }
++                main();
++                """,
++
++    ecmaVersion: ECMAScriptVersion.es6,
++
++    crashTests: ["fuzzilli('FUZZILLI_CRASH', 0)", "fuzzilli('FUZZILLI_CRASH', 1)"],
++
++    additionalCodeGenerators: WeightedList<CodeGenerator>([]),
++    
++    disabledCodeGenerators: [],
++
++    additionalBuiltins: [
++        "gc" : .function([] => .undefined)
++    ]
++)
++
+ let profiles = [
+     "qjs": qjsProfile,
+     "jsc": jscProfile,
+@@ -39,4 +66,5 @@ let profiles = [
+     "v8": v8Profile,
+     "duktape": duktapeProfile,
+     "jerryscript": jerryscriptProfile,
++    "serenity": serenityProfile,
+ ]