From bf3470c1610458eae0882b74903760a6f8231856 Mon Sep 17 00:00:00 2001
From: Daniil Nikolenko <qoo2p5@gmail.com>
Date: Thu, 8 Jul 2021 23:40:53 +0300
Subject: [PATCH] Fix UB in CreateVectorOfStructs in case of an empty vector:
 avoid calling memcpy in this case (#6726)

---
 include/flatbuffers/flatbuffers.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/flatbuffers/flatbuffers.h b/include/flatbuffers/flatbuffers.h
index c073f3b05..0f57f9b0e 100644
--- a/include/flatbuffers/flatbuffers.h
+++ b/include/flatbuffers/flatbuffers.h
@@ -1914,7 +1914,9 @@ class FlatBufferBuilder {
   template<typename T>
   Offset<Vector<const T *>> CreateVectorOfStructs(const T *v, size_t len) {
     StartVector(len * sizeof(T) / AlignOf<T>(), AlignOf<T>());
-    PushBytes(reinterpret_cast<const uint8_t *>(v), sizeof(T) * len);
+    if (len > 0) {
+      PushBytes(reinterpret_cast<const uint8_t *>(v), sizeof(T) * len);
+    }
     return Offset<Vector<const T *>>(EndVector(len));
   }