From bc74013f983084fc658b2783ee00a53ad94742cf Mon Sep 17 00:00:00 2001
From: Alexey Milovidov <milovidov@yandex-team.ru>
Date: Thu, 25 Jul 2019 23:10:33 +0300
Subject: [PATCH] Fixed UBSan report in ProtobufWriter

---
 dbms/src/Formats/ProtobufWriter.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/dbms/src/Formats/ProtobufWriter.cpp b/dbms/src/Formats/ProtobufWriter.cpp
index bca3449cb59..fcaedcab2a0 100644
--- a/dbms/src/Formats/ProtobufWriter.cpp
+++ b/dbms/src/Formats/ProtobufWriter.cpp
@@ -141,7 +141,8 @@ void ProtobufWriter::SimpleWriter::endMessage()
     size_t size_of_message = buffer.size() - num_bytes_skipped;
     writeVarint(size_of_message, out);
     for (const auto & piece : pieces)
-        out.write(reinterpret_cast<char *>(&buffer[piece.start]), piece.end - piece.start);
+        if (piece.end > piece.start)
+            out.write(reinterpret_cast<char *>(&buffer[piece.start]), piece.end - piece.start);
     buffer.clear();
     pieces.clear();
     num_bytes_skipped = 0;