Error checking for length parameter of external array constructors in shell

src/d8.cc

Index: src/d8.cc
diff --git a/src/d8.cc b/src/d8.cc
index 56a43ad2411e375f529beca5a62dd6c2df5469ac..ae86243fd224b711b3a4b6246743fe31d59ad712 100644
--- a/src/d8.cc
+++ b/src/d8.cc
@@ -223,14 +223,28 @@ Handle<Value> Shell::Load(const Arguments& args) {
 
 Handle<Value> Shell::CreateExternalArray(const Arguments& args,
                                          ExternalArrayType type,
-                                         int element_size) {
+                                         size_t element_size) {
   if (args.Length() != 1) {
     return ThrowException(
         String::New("Array constructor needs one parameter."));
   }
-  int length = args[0]->Int32Value();
-  void* data = malloc(length * element_size);
-  memset(data, 0, length * element_size);
+  if (args[0]->Int32Value() < 0) {
+    return ThrowException(String::New("Array length must not be negative."));
+  }
+  size_t length = static_cast<size_t>(args[0]->Int32Value());
+  if (length > static_cast<size_t>(internal::ExternalArray::kMaxLength)) {
+    return ThrowException(String::New("Array length exceeds maximum length."));
+  }
+  size_t malloc_size = length * element_size;
+  // Check for overflow in the multiplication.
+  if (malloc_size < length || malloc_size < element_size) {
+    return ThrowException(String::New("Array size exceeds memory limit."));
+  }
+  void* data = malloc(malloc_size);
+  if (data == NULL) {
+    return ThrowException(String::New("Memory allocation failed."));
+  }
+  memset(data, 0, malloc_size);
   Handle<Object> array = Object::New();
   Persistent<Object> persistent_array = Persistent<Object>::New(array);
   persistent_array.MakeWeak(data, ExternalArrayWeakCallback);