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| 1 | +#ifdef FUZZILLI_ENABLED |
| 2 | +#include "JavaScriptCore/CallFrame.h" |
| 3 | +#include "JavaScriptCore/Identifier.h" |
| 4 | +#include "JavaScriptCore/JSGlobalObject.h" |
| 5 | +#include "ZigGlobalObject.h" |
| 6 | +#include "root.h" |
| 7 | +#include "wtf/text/WTFString.h" |
| 8 | +#include <cerrno> |
| 9 | +#include <csignal> |
| 10 | +#include <cstdlib> |
| 11 | +#include <cstring> |
| 12 | +#include <fcntl.h> |
| 13 | +#include <sanitizer/asan_interface.h> |
| 14 | +#include <sys/mman.h> |
| 15 | +#include <sys/stat.h> |
| 16 | +#include <unistd.h> |
| 17 | + |
| 18 | +#define REPRL_DWFD 103 |
| 19 | + |
| 20 | +extern "C" { |
| 21 | + |
| 22 | +// Signal handler to ensure output is flushed before crash |
| 23 | +static void fuzzilliSignalHandler(int sig) |
| 24 | +{ |
| 25 | + // Flush all output |
| 26 | + fflush(stdout); |
| 27 | + fflush(stderr); |
| 28 | + fsync(STDOUT_FILENO); |
| 29 | + fsync(STDERR_FILENO); |
| 30 | + |
| 31 | + // Re-raise the signal with default handler |
| 32 | + signal(sig, SIG_DFL); |
| 33 | + raise(sig); |
| 34 | +} |
| 35 | + |
| 36 | +// Implementation of the global fuzzilli() function for Bun |
| 37 | +// This function is used by Fuzzilli to: |
| 38 | +// 1. Test crash detection with fuzzilli('FUZZILLI_CRASH', type) |
| 39 | +// 2. Print output with fuzzilli('FUZZILLI_PRINT', value) |
| 40 | +static JSC::EncodedJSValue JSC_HOST_CALL_ATTRIBUTES functionFuzzilli(JSC::JSGlobalObject* globalObject, JSC::CallFrame* callFrame) |
| 41 | +{ |
| 42 | + JSC::VM& vm = globalObject->vm(); |
| 43 | + auto scope = DECLARE_THROW_SCOPE(vm); |
| 44 | + |
| 45 | + if (callFrame->argumentCount() < 1) { |
| 46 | + return JSC::JSValue::encode(JSC::jsUndefined()); |
| 47 | + } |
| 48 | + |
| 49 | + JSC::JSValue arg0 = callFrame->argument(0); |
| 50 | + WTF::String command = arg0.toWTFString(globalObject); |
| 51 | + RETURN_IF_EXCEPTION(scope, JSC::JSValue::encode(JSC::jsUndefined())); |
| 52 | + |
| 53 | + if (command == "FUZZILLI_CRASH"_s) { |
| 54 | + // Fuzzilli uses this to test crash detection |
| 55 | + // The second argument is an integer specifying the crash type |
| 56 | + int crashType = 0; |
| 57 | + if (callFrame->argumentCount() >= 2) { |
| 58 | + JSC::JSValue arg1 = callFrame->argument(1); |
| 59 | + crashType = arg1.toInt32(globalObject); |
| 60 | + } |
| 61 | + |
| 62 | + // Print the crash type for debugging |
| 63 | + fprintf(stdout, "FUZZILLI_CRASH: %d\n", crashType); |
| 64 | + fflush(stdout); |
| 65 | + |
| 66 | + // Trigger different types of crashes for testing (similar to V8 implementation) |
| 67 | + switch (crashType) { |
| 68 | + case 0: |
| 69 | + // IMMEDIATE_CRASH - Simple abort |
| 70 | + std::abort(); |
| 71 | + break; |
| 72 | + |
| 73 | + case 1: |
| 74 | + // CHECK failure - assertion in release builds |
| 75 | + // Use __builtin_trap() for a direct crash |
| 76 | + __builtin_trap(); |
| 77 | + break; |
| 78 | + |
| 79 | + case 2: |
| 80 | + // DCHECK failure - always crash (use trap instead of assert which is disabled in release) |
| 81 | + __builtin_trap(); |
| 82 | + break; |
| 83 | + |
| 84 | + case 3: |
| 85 | + // Wild write - heap buffer overflow (will be caught by ASAN) |
| 86 | + { |
| 87 | + volatile char* buffer = new char[10]; |
| 88 | + buffer[20] = 'x'; // Write past the end - ASAN should catch this |
| 89 | + // Don't delete to make it more obvious |
| 90 | + } |
| 91 | + break; |
| 92 | + |
| 93 | + case 4: |
| 94 | + // Use-after-free (will be caught by ASAN) |
| 95 | + { |
| 96 | + volatile char* buffer = new char[10]; |
| 97 | + delete[] buffer; |
| 98 | + buffer[0] = 'x'; // Use after free - ASAN should catch this |
| 99 | + } |
| 100 | + break; |
| 101 | + |
| 102 | + case 5: |
| 103 | + // Null pointer dereference |
| 104 | + { |
| 105 | + volatile int* ptr = nullptr; |
| 106 | + *ptr = 42; |
| 107 | + } |
| 108 | + break; |
| 109 | + |
| 110 | + case 6: |
| 111 | + // Stack buffer overflow (will be caught by ASAN) |
| 112 | + { |
| 113 | + volatile char buffer[10]; |
| 114 | + volatile char* p = const_cast<char*>(buffer); |
| 115 | + p[20] = 'x'; // Write past stack buffer |
| 116 | + } |
| 117 | + break; |
| 118 | + |
| 119 | + case 7: |
| 120 | + // Double free (will be caught by ASAN) |
| 121 | + { |
| 122 | + char* buffer = new char[10]; |
| 123 | + delete[] buffer; |
| 124 | + delete[] buffer; // Double free - ASAN should catch this |
| 125 | + } |
| 126 | + break; |
| 127 | + |
| 128 | + case 8: |
| 129 | + // Verify DEBUG or ASAN is enabled |
| 130 | + // Expected to be compiled with debug or ASAN, don't crash |
| 131 | + fprintf(stdout, "DEBUG or ASAN is enabled\n"); |
| 132 | + fflush(stdout); |
| 133 | + break; |
| 134 | + |
| 135 | + default: |
| 136 | + // Unknown crash type, just abort |
| 137 | + std::abort(); |
| 138 | + break; |
| 139 | + } |
| 140 | + } else if (command == "FUZZILLI_PRINT"_s) { |
| 141 | + // Optional: Print the second argument |
| 142 | + if (callFrame->argumentCount() >= 2) { |
| 143 | + JSC::JSValue arg1 = callFrame->argument(1); |
| 144 | + WTF::String output = arg1.toWTFString(globalObject); |
| 145 | + RETURN_IF_EXCEPTION(scope, JSC::JSValue::encode(JSC::jsUndefined())); |
| 146 | + |
| 147 | + FILE* f = fdopen(REPRL_DWFD, "w"); |
| 148 | + fprintf(f, "%s\n", output.utf8().data()); |
| 149 | + fflush(f); |
| 150 | + } |
| 151 | + } |
| 152 | + |
| 153 | + return JSC::JSValue::encode(JSC::jsUndefined()); |
| 154 | +} |
| 155 | + |
| 156 | +// ============================================================================ |
| 157 | +// Coverage instrumentation for Fuzzilli |
| 158 | +// Based on workerd implementation |
| 159 | +// Only enabled when ASAN is active |
| 160 | +// ============================================================================ |
| 161 | + |
| 162 | +#define SHM_SIZE 0x200000 |
| 163 | +#define MAX_EDGES ((SHM_SIZE - 4) * 8) |
| 164 | + |
| 165 | +struct shmem_data { |
| 166 | + uint32_t num_edges; |
| 167 | + unsigned char edges[]; |
| 168 | +}; |
| 169 | + |
| 170 | +// Global coverage data |
| 171 | +static struct shmem_data* __shmem = nullptr; |
| 172 | +static uint32_t* __edges_start = nullptr; |
| 173 | +static uint32_t* __edges_stop = nullptr; |
| 174 | + |
| 175 | +// Reset edge guards for next iteration |
| 176 | +static void __sanitizer_cov_reset_edgeguards() |
| 177 | +{ |
| 178 | + if (!__edges_start || !__edges_stop) return; |
| 179 | + uint64_t N = 0; |
| 180 | + for (uint32_t* x = __edges_start; x < __edges_stop && N < MAX_EDGES; x++) { |
| 181 | + *x = ++N; |
| 182 | + } |
| 183 | +} |
| 184 | + |
| 185 | +// Called by the compiler to initialize coverage instrumentation |
| 186 | +extern "C" void __sanitizer_cov_trace_pc_guard_init(uint32_t* start, uint32_t* stop) |
| 187 | +{ |
| 188 | + // Avoid duplicate initialization |
| 189 | + if (start == stop || *start) return; |
| 190 | + |
| 191 | + if (__edges_start != nullptr || __edges_stop != nullptr) { |
| 192 | + fprintf(stderr, "[COV] Coverage instrumentation is only supported for a single module\n"); |
| 193 | + _exit(-1); |
| 194 | + } |
| 195 | + |
| 196 | + __edges_start = start; |
| 197 | + __edges_stop = stop; |
| 198 | + |
| 199 | + // Map the shared memory region |
| 200 | + const char* shm_key = getenv("SHM_ID"); |
| 201 | + if (!shm_key) { |
| 202 | + fprintf(stderr, "[COV] no shared memory bitmap available, using malloc\n"); |
| 203 | + __shmem = (struct shmem_data*)malloc(SHM_SIZE); |
| 204 | + if (!__shmem) { |
| 205 | + fprintf(stderr, "[COV] Failed to allocate coverage bitmap\n"); |
| 206 | + _exit(-1); |
| 207 | + } |
| 208 | + memset(__shmem, 0, SHM_SIZE); |
| 209 | + } else { |
| 210 | + int fd = shm_open(shm_key, O_RDWR, S_IREAD | S_IWRITE); |
| 211 | + if (fd <= -1) { |
| 212 | + fprintf(stderr, "[COV] Failed to open shared memory region: %s\n", strerror(errno)); |
| 213 | + _exit(-1); |
| 214 | + } |
| 215 | + |
| 216 | + __shmem = (struct shmem_data*)mmap(0, SHM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); |
| 217 | + if (__shmem == MAP_FAILED) { |
| 218 | + fprintf(stderr, "[COV] Failed to mmap shared memory region\n"); |
| 219 | + _exit(-1); |
| 220 | + } |
| 221 | + } |
| 222 | + |
| 223 | + __sanitizer_cov_reset_edgeguards(); |
| 224 | + __shmem->num_edges = stop - start; |
| 225 | + fprintf(stderr, "[COV] Coverage instrumentation initialized with %u edges\n", __shmem->num_edges); |
| 226 | +} |
| 227 | + |
| 228 | +// Called by the compiler for each edge |
| 229 | +extern "C" void __sanitizer_cov_trace_pc_guard(uint32_t* guard) |
| 230 | +{ |
| 231 | + // There's a small race condition here: if this function executes in two threads for the same |
| 232 | + // edge at the same time, the first thread might disable the edge (by setting the guard to zero) |
| 233 | + // before the second thread fetches the guard value (and thus the index). However, our |
| 234 | + // instrumentation ignores the first edge (see libcoverage.c) and so the race is unproblematic. |
| 235 | + if (!__shmem) return; |
| 236 | + uint32_t index = *guard; |
| 237 | + // If this function is called before coverage instrumentation is properly initialized we want to return early. |
| 238 | + if (!index) return; |
| 239 | + __shmem->edges[index / 8] |= 1 << (index % 8); |
| 240 | + *guard = 0; |
| 241 | +} |
| 242 | + |
| 243 | +// Function to reset coverage for next REPRL iteration |
| 244 | +// This should be called after each script execution |
| 245 | +JSC_DEFINE_HOST_FUNCTION(jsResetCoverage, (JSC::JSGlobalObject * globalObject, JSC::CallFrame*)) |
| 246 | +{ |
| 247 | + __sanitizer_cov_reset_edgeguards(); |
| 248 | + return JSC::JSValue::encode(JSC::jsUndefined()); |
| 249 | +} |
| 250 | + |
| 251 | +// Register the fuzzilli() function on a Bun global object |
| 252 | +void Bun__REPRL__registerFuzzilliFunctions(Zig::GlobalObject* globalObject) |
| 253 | +{ |
| 254 | + JSC::VM& vm = globalObject->vm(); |
| 255 | + |
| 256 | + // Install signal handlers to ensure output is flushed before crashes |
| 257 | + // This is important for ASAN output to be captured |
| 258 | + signal(SIGABRT, fuzzilliSignalHandler); |
| 259 | + signal(SIGSEGV, fuzzilliSignalHandler); |
| 260 | + signal(SIGILL, fuzzilliSignalHandler); |
| 261 | + signal(SIGFPE, fuzzilliSignalHandler); |
| 262 | + |
| 263 | + globalObject->putDirectNativeFunction( |
| 264 | + vm, |
| 265 | + globalObject, |
| 266 | + JSC::Identifier::fromString(vm, "fuzzilli"_s), |
| 267 | + 2, // max 2 arguments |
| 268 | + functionFuzzilli, |
| 269 | + JSC::ImplementationVisibility::Public, |
| 270 | + JSC::NoIntrinsic, |
| 271 | + JSC::PropertyAttribute::DontEnum | JSC::PropertyAttribute::DontDelete); |
| 272 | + |
| 273 | + globalObject->putDirectNativeFunction( |
| 274 | + vm, |
| 275 | + globalObject, |
| 276 | + JSC::Identifier::fromString(vm, "resetCoverage"_s), |
| 277 | + 0, |
| 278 | + jsResetCoverage, |
| 279 | + JSC::ImplementationVisibility::Public, |
| 280 | + JSC::NoIntrinsic, |
| 281 | + JSC::PropertyAttribute::DontEnum | JSC::PropertyAttribute::DontDelete); |
| 282 | +} |
| 283 | + |
| 284 | +} // extern "C" |
| 285 | + |
| 286 | +#endif // FUZZILLI_ENABLED |
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