Segfault in TensorFlow if `tf.histogram_fixed_width` is called with NaN values

@@ -50,6 +50,15 @@ struct HistogramFixedWidthFunctor<CPUDevice, T, Tout> {
                         static_cast<double>(nbins);
     const double nbins_minus_1 = static_cast<double>(nbins - 1);
 
+    // We cannot handle NANs in the algorithm below (due to the case to int32)
+    const Eigen::Tensor<int32, 1, 1> nans_tensor =
+        values.isnan().template cast<int32>();
+    const Eigen::Tensor<int32, 0, 1> reduced_tensor = nans_tensor.sum();
+    const int num_nans = reduced_tensor(0);
+    if (num_nans > 0) {
+      return errors::InvalidArgument("Histogram values must not contain NaN");
+    }
+
     // The calculation is done by finding the slot of each value in `values`.
     // With [a, b]:
     //   step = (b - a) / nbins
@@ -98,12 +107,12 @@ class HistogramFixedWidthOp : public OpKernel {
     const auto nbins = nbins_tensor.scalar<int32>()();
 
     OP_REQUIRES(
-        ctx, (value_range(0) < value_range(1)),
+        ctx, value_range(0) < value_range(1),
         errors::InvalidArgument("value_range should satisfy value_range[0] < "
                                 "value_range[1], but got '[",
                                 value_range(0), ", ", value_range(1), "]'"));
     OP_REQUIRES(
-        ctx, (nbins > 0),
+        ctx, nbins > 0,
         errors::InvalidArgument("nbins should be a positive number, but got '",
                                 nbins, "'"));