From f726ecd6ea29f9da8e67cc4b8441f1ff22a45610 Mon Sep 17 00:00:00 2001
From: Christopher Jones <chrisdjones15@gmail.com>
Date: Tue, 26 Apr 2022 12:07:12 -0500
Subject: [PATCH] Handle empty table when writing NanoAOD

Avoid dereferencing a null pointer when writing an empty table.
This was uncovered by the UBSAN checks.
---
 PhysicsTools/NanoAOD/plugins/TableOutputBranches.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/PhysicsTools/NanoAOD/plugins/TableOutputBranches.h b/PhysicsTools/NanoAOD/plugins/TableOutputBranches.h
index f5619e27a3b6c..f408e65759e38 100644
--- a/PhysicsTools/NanoAOD/plugins/TableOutputBranches.h
+++ b/PhysicsTools/NanoAOD/plugins/TableOutputBranches.h
@@ -54,7 +54,9 @@ class TableOutputBranches {
     int idx = tab.columnIndex(pair.name);
     if (idx == -1)
       throw cms::Exception("LogicError", "Missing column in input for " + m_baseName + "_" + pair.name);
-    pair.branch->SetAddress(const_cast<T *>(&tab.columnData<T>(idx).front()));  // SetAddress should take a const * !
+    pair.branch->SetAddress(
+        tab.size() == 0 ? static_cast<T *>(nullptr)
+                        : const_cast<T *>(&tab.columnData<T>(idx).front()));  // SetAddress should take a const * !
   }
 };