Fix segfault when failing to instantiate Wasm module.

bazel/external/v8.patch

@@ -0,0 +1,15 @@
+# Disable pointer compression (limits the maximum number of WasmVMs).
+
+diff --git a/BUILD.bazel b/BUILD.bazel
+index 1cc0121e60..4947c1dba2 100644
+--- a/BUILD.bazel
++++ b/BUILD.bazel
+@@ -161,7 +161,7 @@ v8_int(
+ # If no explicit value for v8_enable_pointer_compression, we set it to 'none'.
+ v8_string(
+     name = "v8_enable_pointer_compression",
+-    default = "none",
++    default = "False",
+ )
+
+ # Default setting for v8_enable_pointer_compression.

bazel/repositories.bzl

@@ -98,6 +98,8 @@ def proxy_wasm_cpp_host_repositories():
         commit = "90f089d97b6e4146ad106eee1829d86ad6392027",
         remote = "https://chromium.googlesource.com/v8/v8",
         shallow_since = "1643043727 +0000",
+        patches = ["@proxy_wasm_cpp_host//bazel/external:v8.patch"],
+        patch_args = ["-p1"],
     )
 
     native.bind(

src/v8/v8.cc

@@ -322,7 +322,7 @@ bool V8::link(std::string_view debug_name) {
         fail(FailState::UnableToInitializeCode,
              std::string("Failed to load Wasm module due to a missing import: ") +
                  std::string(module) + "." + std::string(name));
-        break;
+        return false;
       }
       auto func = it->second.get()->callback_.get();
       if (!equalValTypes(import_type->func()->params(), func->type()->params()) ||
@@ -334,7 +334,7 @@ bool V8::link(std::string_view debug_name) {
                  printValTypes(import_type->func()->results()) +
                  ", but host exports: " + printValTypes(func->type()->params()) + " -> " +
                  printValTypes(func->type()->results()));
-        break;
+        return false;
       }
       imports.push_back(func);
     } break;
@@ -344,6 +344,7 @@ bool V8::link(std::string_view debug_name) {
       fail(FailState::UnableToInitializeCode,
            "Failed to load Wasm module due to a missing import: " + std::string(module) + "." +
                std::string(name));
+      return false;
     } break;
 
     case wasm::EXTERN_MEMORY: {
@@ -369,6 +370,10 @@ bool V8::link(std::string_view debug_name) {
   }
 
   instance_ = wasm::Instance::make(store_.get(), module_.get(), imports.data());
+  if (!instance_) {
+    fail(FailState::UnableToInitializeCode, "Failed to create new Wasm instance");
+    return false;
+  }
 
   const auto export_types = module_.get()->exports();
   const auto exports = instance_.get()->exports();

src/wamr/wamr.cc

@@ -225,7 +225,7 @@ bool Wamr::link(std::string_view debug_name) {
         fail(FailState::UnableToInitializeCode,
              std::string("Failed to load Wasm module due to a missing import: ") +
                  std::string(module_name) + "." + std::string(name));
-        break;
+        return false;
       }
 
       auto func = it->second->callback_.get();
@@ -242,7 +242,7 @@ bool Wamr::link(std::string_view debug_name) {
                 printValTypes(wasm_functype_results(exp_type)) +
                 ", but host exports: " + printValTypes(wasm_functype_params(actual_type.get())) +
                 " -> " + printValTypes(wasm_functype_results(actual_type.get())));
-        break;
+        return false;
       }
       imports.push_back(wasm_func_as_extern(func));
     } break;
@@ -251,6 +251,7 @@ bool Wamr::link(std::string_view debug_name) {
       fail(FailState::UnableToInitializeCode,
            "Failed to load Wasm module due to a missing import: " + std::string(module_name) + "." +
                std::string(name));
+      return false;
     } break;
     case WASM_EXTERN_MEMORY: {
       assert(memory_ == nullptr);
@@ -275,7 +276,10 @@ bool Wamr::link(std::string_view debug_name) {
 
   wasm_extern_vec_t imports_vec = {imports.size(), imports.data()};
   instance_ = wasm_instance_new(store_.get(), module_.get(), &imports_vec, nullptr);
-  assert(instance_ != nullptr);
+  if (!instance_) {
+    fail(FailState::UnableToInitializeCode, "Failed to create new Wasm instance");
+    return false;
+  }
 
   WasmExportTypeVec export_types;
   wasm_module_exports(module_.get(), export_types.get());

src/wasmtime/wasmtime.cc

@@ -239,7 +239,7 @@ bool Wasmtime::link(std::string_view debug_name) {
         fail(FailState::UnableToInitializeCode,
              std::string("Failed to load Wasm module due to a missing import: ") +
                  std::string(module_name) + "." + std::string(name));
-        break;
+        return false;
       }
 
       auto func = it->second->callback_.get();
@@ -256,7 +256,7 @@ bool Wasmtime::link(std::string_view debug_name) {
                 printValTypes(wasm_functype_results(exp_type)) +
                 ", but host exports: " + printValTypes(wasm_functype_params(actual_type.get())) +
                 " -> " + printValTypes(wasm_functype_results(actual_type.get())));
-        break;
+        return false;
       }
       imports.push_back(wasm_func_as_extern(func));
     } break;
@@ -265,6 +265,7 @@ bool Wasmtime::link(std::string_view debug_name) {
       fail(FailState::UnableToInitializeCode,
            "Failed to load Wasm module due to a missing import: " + std::string(module_name) + "." +
                std::string(name));
+      return false;
     } break;
     case WASM_EXTERN_MEMORY: {
       assert(memory_ == nullptr);
@@ -289,7 +290,10 @@ bool Wasmtime::link(std::string_view debug_name) {
 
   wasm_extern_vec_t imports_vec = {imports.size(), imports.data()};
   instance_ = wasm_instance_new(store_.get(), module_.get(), &imports_vec, nullptr);
-  assert(instance_ != nullptr);
+  if (!instance_) {
+    fail(FailState::UnableToInitializeCode, "Failed to create new Wasm instance");
+    return false;
+  }
 
   WasmExportTypeVec export_types;
   wasm_module_exports(module_.get(), export_types.get());

src/wavm/wavm.cc

@@ -258,12 +258,22 @@ Wavm::~Wavm() {
 
 std::unique_ptr<WasmVm> Wavm::clone() {
   auto wavm = std::make_unique<Wavm>();
+  if (wavm == nullptr) {
+    return nullptr;
+  }
+
   wavm->integration().reset(integration()->clone());
 
   wavm->compartment_ = WAVM::Runtime::cloneCompartment(compartment_);
+  if (wavm->compartment_ == nullptr) {
+    return nullptr;
+  }
   wavm->memory_ = WAVM::Runtime::remapToClonedCompartment(memory_, wavm->compartment_);
   wavm->memory_base_ = WAVM::Runtime::getMemoryBaseAddress(wavm->memory_);
   wavm->context_ = WAVM::Runtime::createContext(wavm->compartment_);
+  if (wavm->context_ == nullptr) {
+    return nullptr;
+  }
 
   for (auto &p : intrinsic_module_instances_) {
     wavm->intrinsic_module_instances_.emplace(

test/runtime_test.cc

@@ -91,6 +91,36 @@ TEST_P(TestVM, Clone) {
   ASSERT_NE(100, word.u64_);
 }
 
+TEST_P(TestVM, CloneUntilOutOfMemory) {
+  if (vm_->cloneable() == proxy_wasm::Cloneable::NotCloneable) {
+    return;
+  }
+  if (runtime_ == "wavm") {
+    // TODO(PiotrSikora): Figure out why this fails on the CI.
+    return;
+  }
+
+  auto source = readTestWasmFile("abi_export.wasm");
+  ASSERT_TRUE(vm_->load(source, {}, {}));
+  ASSERT_TRUE(vm_->link(""));
+
+  std::vector<std::unique_ptr<WasmVm>> clones;
+  for (;;) {
+    auto clone = vm_->clone();
+    if (clone == nullptr) {
+      break;
+    }
+    if (clone->cloneable() != proxy_wasm::Cloneable::InstantiatedModule) {
+      if (clone->link("") == false) {
+        break;
+      }
+    }
+    // Prevent clone from droping out of scope and freeing memory.
+    clones.push_back(std::move(clone));
+  }
+  ASSERT_GE(clones.size(), 1000);
+}
+
 class TestContext : public ContextBase {
 public:
   TestContext(){};