fix output var may be nullptr and cause segment fault bug (#40079)

paddle/fluid/framework/operator.cc

@@ -2106,15 +2106,19 @@ void OperatorWithKernel::BuildPhiKernelContext(
     for (size_t offset = 0; offset < outs_vector.size(); ++offset) {
       phi::TensorBase* tensor_out = nullptr;
       auto* var = outs_vector[offset];
-      if (var->template IsType<framework::LoDTensor>()) {
-        tensor_out = var->template GetMutable<framework::LoDTensor>();
-      } else if (var->template IsType<phi::SelectedRows>()) {
-        tensor_out = var->template GetMutable<phi::SelectedRows>();
-      } else {
-        PADDLE_THROW(platform::errors::Unimplemented(
-            "Unsupported output `%s` type when call pt kernel.",
-            framework::ToTypeName(var->Type())));
+
+      if (var) {
+        if (var->template IsType<framework::LoDTensor>()) {
+          tensor_out = var->template GetMutable<framework::LoDTensor>();
+        } else if (var->template IsType<phi::SelectedRows>()) {
+          tensor_out = var->template GetMutable<phi::SelectedRows>();
+        } else {
+          PADDLE_THROW(platform::errors::Unimplemented(
+              "Unsupported output `%s` type when call pt kernel.",
+              framework::ToTypeName(var->Type())));
+        }
       }
+
       pt_kernel_context->EmplaceBackOutputWithoutSetRange(tensor_out);
     }
 

paddle/fluid/imperative/prepared_operator.h

@@ -314,15 +314,18 @@ void BuildDygraphPhiKernelContext(
 
       phi::TensorBase* tensor_out = nullptr;
       auto* var = outs_vector[offset]->MutableVar();
-      if (var->template IsType<phi::DenseTensor>()) {
-        tensor_out = var->template GetMutable<phi::DenseTensor>();
-      } else if (var->template IsType<phi::SelectedRows>()) {
-        tensor_out = var->template GetMutable<phi::SelectedRows>();
-      } else {
-        PADDLE_THROW(platform::errors::Unimplemented(
-            "Unsupported output `%s` type when call pt kernel.",
-            framework::ToTypeName(var->Type())));
+      if (var) {
+        if (var->template IsType<phi::DenseTensor>()) {
+          tensor_out = var->template GetMutable<phi::DenseTensor>();
+        } else if (var->template IsType<phi::SelectedRows>()) {
+          tensor_out = var->template GetMutable<phi::SelectedRows>();
+        } else {
+          PADDLE_THROW(platform::errors::Unimplemented(
+              "Unsupported output `%s` type when call pt kernel.",
+              framework::ToTypeName(var->Type())));
+        }
       }
+
       kernel_ctx->EmplaceBackOutputWithoutSetRange(tensor_out);
     }
     kernel_ctx->AssignOutputRange(std::make_pair(start_idx, end_idx), i);