[fuzzing] execute every exported function (bytecodealliance#3959)

- Enhance wasm mutator fuzz tests by adding export function execution and random value generation
- Use --fuel to limit  loop size
- Use predefined values and enhance argument logging in execution

Author: lum1n0us

tests/fuzz/wasm-mutator-fuzz/smith_wasm.sh

@@ -41,7 +41,9 @@ function try_generate_wasm()
     printf -- "-- output ${GENERATED_WASM_NAME} in %d retries\n" $try_i
 }
 
-WASM_SHAPE=" --allow-invalid-funcs true \
+WASM_SHAPE=" --ensure-termination \
+--export-everything true \
+--fuel 7 \
 --generate-custom-sections true \
 --min-funcs 5 \
 --max-instructions 1024 \

tests/fuzz/wasm-mutator-fuzz/wasm_mutator_fuzz.cc

@@ -13,6 +13,149 @@
 
 using namespace std;
 
+static bool
+is_supported_val_kind(wasm_valkind_t kind)
+{
+    return kind == WASM_I32 || kind == WASM_I64 || kind == WASM_F32
+           || kind == WASM_F64 || kind == WASM_EXTERNREF
+           || kind == WASM_FUNCREF;
+}
+
+static wasm_val_t
+pre_defined_val(wasm_valkind_t kind)
+{
+    if (kind == WASM_I32) {
+        return wasm_val_t{ .kind = WASM_I32, .of = { .i32 = 2025 } };
+    }
+    else if (kind == WASM_I64) {
+        return wasm_val_t{ .kind = WASM_I64, .of = { .i64 = 168 } };
+    }
+    else if (kind == WASM_F32) {
+        return wasm_val_t{ .kind = WASM_F32, .of = { .f32 = 3.14159f } };
+    }
+    else if (kind == WASM_F64) {
+        return wasm_val_t{ .kind = WASM_F64, .of = { .f64 = 2.71828 } };
+    }
+    else if (kind == WASM_EXTERNREF) {
+        return wasm_val_t{ .kind = WASM_EXTERNREF,
+                           .of = { .foreign = 0xabcddead } };
+    }
+    // because aft is_supported_val_kind() check, so we can safely return as
+    // WASM_FUNCREF
+    else {
+        return wasm_val_t{ .kind = WASM_FUNCREF, .of = { .ref = nullptr } };
+    }
+}
+void
+print_execution_args(const wasm_export_t &export_type,
+                     const std::vector<wasm_val_t> &args, unsigned param_count)
+{
+    std::cout << "[EXECUTION] " << export_type.name << "(";
+    for (unsigned p_i = 0; p_i < param_count; p_i++) {
+        if (p_i != 0) {
+            std::cout << ", ";
+        }
+
+        switch (args[p_i].kind) {
+            case WASM_I32:
+                std::cout << "i32:" << args[p_i].of.i32;
+                break;
+            case WASM_I64:
+                std::cout << "i64:" << args[p_i].of.i64;
+                break;
+            case WASM_F32:
+                std::cout << "f32:" << args[p_i].of.f32;
+                break;
+            case WASM_F64:
+                std::cout << "f64:" << args[p_i].of.f64;
+                break;
+            case WASM_EXTERNREF:
+                std::cout << "externref:" << args[p_i].of.foreign;
+                break;
+            default:
+                // because aft is_supported_val_kind() check, so we can safely
+                // return as WASM_FUNCREF
+                std::cout << "funcref:" << args[p_i].of.ref;
+                break;
+        }
+    }
+    std::cout << ")" << std::endl;
+}
+
+static bool
+execute_export_functions(wasm_module_t module, wasm_module_inst_t inst)
+{
+    int32_t export_count = wasm_runtime_get_export_count(module);
+
+    for (int e_i = 0; e_i < export_count; e_i++) {
+        wasm_export_t export_type = { 0 };
+        wasm_runtime_get_export_type(module, e_i, &export_type);
+
+        if (export_type.kind != WASM_IMPORT_EXPORT_KIND_FUNC) {
+            continue;
+        }
+
+        wasm_function_inst_t func =
+            wasm_runtime_lookup_function(inst, export_type.name);
+        if (!func) {
+            std::cout << "Failed to lookup function: " << export_type.name
+                      << std::endl;
+            continue;
+        }
+
+        wasm_func_type_t func_type = export_type.u.func_type;
+        uint32_t param_count = wasm_func_type_get_param_count(func_type);
+
+        /* build arguments */
+        std::vector<wasm_val_t> args;
+        for (unsigned p_i = 0; p_i < param_count; p_i++) {
+            wasm_valkind_t param_type =
+                wasm_func_type_get_param_valkind(func_type, p_i);
+
+            if (!is_supported_val_kind(param_type)) {
+                std::cout
+                    << "Bypass execution because of unsupported value kind: "
+                    << param_type << std::endl;
+                return true;
+            }
+
+            wasm_val_t arg = pre_defined_val(param_type);
+            args.push_back(arg);
+        }
+
+        /* build results storage */
+        uint32_t result_count = wasm_func_type_get_result_count(func_type);
+        std::vector<wasm_val_t> results = std::vector<wasm_val_t>(result_count);
+
+        print_execution_args(export_type, args, param_count);
+
+        /* execute the function */
+        wasm_exec_env_t exec_env = wasm_runtime_get_exec_env_singleton(inst);
+        if (!exec_env) {
+            std::cout << "Failed to get exec env" << std::endl;
+            return false;
+        }
+
+        bool ret = wasm_runtime_call_wasm_a(exec_env, func, result_count,
+                                            results.data(), param_count, args.data());
+        if (!ret) {
+            const char *exception = wasm_runtime_get_exception(inst);
+            if (!exception) {
+                std::cout << "[EXECUTION] " << export_type.name
+                          << "() failed. No exception info." << std::endl;
+            }
+            else {
+                std::cout << "[EXECUTION] " << export_type.name << "() failed. "
+                          << exception << std::endl;
+            }
+        }
+
+        wasm_runtime_clear_exception(inst);
+    }
+
+    return true;
+}
+
 extern "C" int
 LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size)
 {
@@ -43,7 +186,7 @@ LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size)
         return 0;
     }
 
-    std::cout << "PASS" << std::endl;
+    execute_export_functions(module, inst);
 
     wasm_runtime_deinstantiate(inst);
     wasm_runtime_unload(module);