Explicitly set buffer_handle to kTfLiteNullBufferHandle when crea…

…ting tensors through `BuildTfLiteTensor`.

The runtime will interpreter buffer_handle == 0 as having a valid delegate, and will dereference nullptr if a delegate is not set. Creating tensors and just zeroing the memory will not properly set buffer_handle to `kTfLiteNullBufferHandle` (which is enum for -1).

Also check for nullptr in `TfLiteDelegateHasValidOpaqueDelegateBuilder` before dereferencing.

PiperOrigin-RevId: 544932843

tensorflow/lite/c/common_internal.h

@@ -103,7 +103,7 @@ inline bool TfLiteDelegateHasValidOpaqueDelegateBuilder(
   //
   // TODO(b/245730811): Consider signalling to clients if the delegate is not
   // initialized cleanly.
-  return delegate->Prepare == nullptr &&
+  return delegate != nullptr && delegate->Prepare == nullptr &&
          delegate->opaque_delegate_builder != nullptr;
 }
 

tensorflow/lite/util.cc

@@ -218,7 +218,9 @@ TfLiteStatus BytesRequired(TfLiteType type, const int* dims, size_t dims_size,
 }
 
 TensorUniquePtr BuildTfLiteTensor() {
-  return TensorUniquePtr((TfLiteTensor*)calloc(1, sizeof(TfLiteTensor)));
+  auto tensor = TensorUniquePtr((TfLiteTensor*)calloc(1, sizeof(TfLiteTensor)));
+  tensor->buffer_handle = kTfLiteNullBufferHandle;
+  return tensor;
 }
 
 TensorUniquePtr BuildTfLiteTensor(TfLiteType type, const std::vector<int>& dims,

tensorflow/lite/util_test.cc

@@ -172,6 +172,7 @@ TEST(FourBitTest, BytesRequiredOdd) {
 TEST(TestMakeUniqueTensor, Valid) {
   TensorUniquePtr t = BuildTfLiteTensor(kTfLiteInt32, {2, 3}, kTfLiteDynamic);
   ASSERT_NE(t.get(), nullptr);
+  ASSERT_EQ(t->buffer_handle, kTfLiteNullBufferHandle);
 
   EXPECT_THAT(t.get(), DimsAre({2, 3}));
   EXPECT_EQ(t->bytes, 24);