From c2eb0c070ca0fdac0411a69f921baf781987306b Mon Sep 17 00:00:00 2001
From: Alex Douglas <alex.netley@gmail.com>
Date: Fri, 5 Jun 2020 19:27:17 +0100
Subject: [PATCH] Fix infinite loop caused when the end of the stream is
 reached (#577)

---
 .../src/Microsoft/Data/SqlClient/SNI/SslOverTdsStream.cs | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SNI/SslOverTdsStream.cs b/src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SNI/SslOverTdsStream.cs
index d0176afa60..74a2e6226d 100644
--- a/src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SNI/SslOverTdsStream.cs
+++ b/src/Microsoft.Data.SqlClient/netcore/src/Microsoft/Data/SqlClient/SNI/SslOverTdsStream.cs
@@ -104,9 +104,16 @@ private async Task<int> ReadInternal(byte[] buffer, int offset, int count, Cance
                     // Account for split packets
                     while (readBytes < TdsEnums.HEADER_LEN)
                     {
-                        readBytes += async ?
+                        var readBytesForHeader = async ?
                             await _stream.ReadAsync(packetData, readBytes, TdsEnums.HEADER_LEN - readBytes, token).ConfigureAwait(false) :
                             _stream.Read(packetData, readBytes, TdsEnums.HEADER_LEN - readBytes);
+
+                        if (readBytesForHeader == 0)
+                        {
+                            throw new EndOfStreamException("End of stream reached");
+                        }
+
+                        readBytes += readBytesForHeader;
                     }
 
                     _packetBytes = (packetData[TdsEnums.HEADER_LEN_FIELD_OFFSET] << 8) | packetData[TdsEnums.HEADER_LEN_FIELD_OFFSET + 1];