fix start function infinite loop bug

src/test/app/Wasm_test.cpp

@@ -850,6 +850,38 @@ struct Wasm_test : public beast::unit_test::suite
             runFinishFunction(localVariableBombHex).has_value() == false);
     }
 
+    void
+    testStartFunctionLoop()
+    {
+        testcase("infinite loop in start function");
+
+        using namespace test::jtx;
+        Env env(*this);
+
+        auto wasmStr = boost::algorithm::unhex(startLoopHex);
+        Bytes wasm(wasmStr.begin(), wasmStr.end());
+        TestLedgerDataProvider ledgerDataProvider(env);
+        ImportVec imports;
+
+        auto& engine = WasmEngine::instance();
+        auto checkRes = engine.check(
+            wasm, "finish", {}, imports, &ledgerDataProvider, env.journal);
+        BEAST_EXPECTS(
+            checkRes == tesSUCCESS, std::to_string(TERtoInt(checkRes)));
+
+        auto re = engine.run(
+            wasm,
+            ESCROW_FUNCTION_NAME,
+            {},
+            imports,
+            &ledgerDataProvider,
+            1'000'000,
+            env.journal);
+        BEAST_EXPECTS(
+            re.error() == tecFAILED_PROCESSING,
+            std::to_string(TERtoInt(re.error())));
+    }
+
     void
     run() override
     {
@@ -878,6 +910,7 @@ struct Wasm_test : public beast::unit_test::suite
         testWasmWasi();
         testWasmSectionCorruption();
 
+        testStartFunctionLoop();
         // perfTest();
     }
 };

src/test/app/wasm_fixtures/fixtures.cpp

@@ -1340,3 +1340,7 @@ extern std::string const infiniteLoopWasmHex =
     "303861373930636664623432626432343732302900490f7461726765745f66656174757265"
     "73042b0f6d757461626c652d676c6f62616c732b087369676e2d6578742b0f726566657265"
     "6e63652d74797065732b0a6d756c746976616c7565";
+
+extern std::string const startLoopHex =
+    "0061736d010000000108026000006000017f03030200010712020573746172740000066669"
+    "6e69736800010801000a0e02070003400c000b0b040041010b";

src/test/app/wasm_fixtures/fixtures.h

@@ -77,3 +77,4 @@ extern std::string const invalidSectionIdHex;
 extern std::string const localVariableBombHex;
 
 extern std::string const infiniteLoopWasmHex;
+extern std::string const startLoopHex;

src/test/app/wasm_fixtures/wat/start_loop.wat

@@ -0,0 +1,22 @@
+(module
+  ;; Function 1: The Infinite Loop
+  (func $run_forever
+    (loop $infinite
+      br $infinite
+    )
+  )
+
+  ;; Function 2: Finish
+  (func $finish (result i32)
+    i32.const 1
+  )
+
+  ;; 1. EXPORT the functions (optional, if you want to call them later)
+  (export "start" (func $run_forever))
+  (export "finish" (func $finish))
+
+  ;; 2. The special start section
+  ;; This tells the VM: "Run function $run_forever immediately
+  ;; when this module is instantiated."
+  (start $run_forever)
+)

src/xrpld/app/wasm/WasmiVM.h

@@ -179,6 +179,10 @@ struct ModuleWrapper
 
     FuncInfo
     getFunc(std::string_view funcName) const;
+
+    wasm_functype_t*
+    getFuncType(std::string_view funcName) const;
+
     wmem
     getMem() const;
 

src/xrpld/app/wasm/detail/WasmiVM.cpp

@@ -249,9 +249,9 @@ ModuleWrapper::ModuleWrapper(
     : module_(init(s, wasmBin, j)), j_(j)
 {
     wasm_module_exports(module_.get(), &exportTypes_.vec_);
+    auto wimports = buildImports(s, imports);
     if (instantiate)
     {
-        auto wimports = buildImports(s, imports);
         addInstance(s, wimports);
     }
 }
@@ -427,6 +427,26 @@ ModuleWrapper::getFunc(std::string_view funcName) const
     return instanceWrap_.getFunc(funcName, exportTypes_);
 }
 
+wasm_functype_t*
+ModuleWrapper::getFuncType(std::string_view funcName) const
+{
+    for (size_t i = 0; i < exportTypes_.vec_.size; i++)
+    {
+        auto const* exp_type(exportTypes_.vec_.data[i]);
+        wasm_name_t const* name = wasm_exporttype_name(exp_type);
+        wasm_externtype_t const* exn_type = wasm_exporttype_type(exp_type);
+        if (wasm_externtype_kind(exn_type) == WASM_EXTERN_FUNC &&
+            funcName == std::string_view(name->data, name->size))
+        {
+            return wasm_externtype_as_functype(
+                const_cast<wasm_externtype_t*>(exn_type));
+        }
+    }
+
+    throw std::runtime_error(
+        "can't find function <" + std::string(funcName) + ">");
+}
+
 wmem
 ModuleWrapper::getMem() const
 {
@@ -889,13 +909,14 @@ WasmiEngine::checkHlp(
     if (wasmCode.empty())
         throw std::runtime_error("empty nodule");
 
-    int const m = addModule(wasmCode, true, -1, imports);
-    if ((m < 0) || !moduleWrap_ || !moduleWrap_->instanceWrap_)
-        throw std::runtime_error("no instance");  // LCOV_EXCL_LINE
+    int const m = addModule(wasmCode, false, -1, imports);
+    if ((m < 0) || !moduleWrap_)
+        throw std::runtime_error("no module");  // LCOV_EXCL_LINE
 
     // Looking for a func and compare parameter types
-    auto const f = getFunc(!funcName.empty() ? funcName : "_start");
-    auto const* ftp = wasm_functype_params(f.second);
+    auto const f =
+        moduleWrap_->getFuncType(!funcName.empty() ? funcName : "_start");
+    auto const* ftp = wasm_functype_params(f);
     auto const p = convertParams(params);
 
     if (int const comp = compareParamTypes(ftp, p); comp >= 0)