From 1e206baedf8bef0334cca3eb92bab134ef525a28 Mon Sep 17 00:00:00 2001
From: Mihai Maruseac <mihaimaruseac@google.com>
Date: Fri, 16 Jul 2021 14:23:21 -0700
Subject: [PATCH] Prevent a division by 0 in division ops.

PiperOrigin-RevId: 385223169
Change-Id: Ia4228960b5d2aa44480385f74bdd70d21a3613c3
---
 tensorflow/lite/kernels/div.cc | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/tensorflow/lite/kernels/div.cc b/tensorflow/lite/kernels/div.cc
index c9eb1db5..aafe00f0 100644
--- a/tensorflow/lite/kernels/div.cc
+++ b/tensorflow/lite/kernels/div.cc
@@ -204,9 +204,23 @@ TfLiteStatus Eval(TfLiteContext* context, TfLiteNode* node) {
   const TfLiteTensor* input2 = GetInput(context, node, kInputTensor2);
   TfLiteTensor* output = GetOutput(context, node, kOutputTensor);
 
-  if (output->type == kTfLiteFloat32 || output->type == kTfLiteInt32) {
+  // TODO(b/193904910): This can written with C++ templates
+#define TF_LITE_CHECK_DIV_NON_ZERO(data_type)                       \
+  const auto* input2_data = GetTensorData<data_type>(input2);       \
+  const size_t input2_elements = input2->bytes / sizeof(data_type); \
+  for (size_t i = 0; i < input2_elements; i++) {                    \
+    TF_LITE_ENSURE(context, input2_data[i] != 0);                   \
+  }
+
+  if (output->type == kTfLiteFloat32) {
+    // Div by zero seems ok in this case, just like in TF case infinities are
+    // returned. So we don't do a check at this point.
+    EvalDiv<kernel_type>(context, node, params, data, input1, input2, output);
+  } else if (output->type == kTfLiteInt32) {
+    TF_LITE_CHECK_DIV_NON_ZERO(int32_t);
     EvalDiv<kernel_type>(context, node, params, data, input1, input2, output);
   } else if (output->type == kTfLiteUInt8) {
+    TF_LITE_CHECK_DIV_NON_ZERO(uint8_t);
     TF_LITE_ENSURE_OK(
         context, EvalQuantized<kernel_type>(context, node, params, data, input1,
                                             input2, output));
@@ -217,6 +231,7 @@ TfLiteStatus Eval(TfLiteContext* context, TfLiteNode* node) {
         output->type);
     return kTfLiteError;
   }
+#undef TF_LITE_CHECK_DIV_NON_ZERO
 
   return kTfLiteOk;
 }
-- 
2.27.0