Getting garbage value while reading packet length from TCP - go

Question

Problem
I am sending packet using tcp, with first 8 byte as long which
contains the actual packet length while receiving it, after some point
it gets wrong packet length which causes the following error "slice
out of range" because the packet length that is received is way bigger
but using TCP Dump I can see it is receiving the correct packet size.
Client TCP Code
package main
import (
"fmt"
"net"
"ByteBuffer"
"log"
"sync"
)
func main() {
conn, err := net.Dial("tcp", "192.168.90.116:8300")
if err != nil {
fmt.Println(err)
return
}
byteBuffer := ByteBuffer.Buffer{
Endian:"big",
}
msg := "Hello World"
totalByteLen := len(msg)
byteBuffer.PutLong(totalByteLen)
byteBuffer.Put([]byte(msg))
log.Println(byteBuffer.Array())
for i:=0;i<1000000000000;i++{
go write(conn, byteBuffer.Array())
}
}
var lck = &sync.Mutex{}
func write(conn net.Conn, data []byte){
lck.Lock()
_, err := conn.Write(data)
lck.Unlock()
if err != nil{
return
}
}
Server TCP Code
func HandleRequest(conn net.Conn){
defer conn.Close()
for {
// creating a 8 byte buffer array
sizeBuf := make([]byte, 8)
// reading from tcp sockets
_, err := conn.Read(sizeBuf)
// converting the packet size to int64
packetSize := int64(binary.BigEndian.Uint64(sizeBuf))
log.Println(packetSize)
if packetSize < 0 {
continue
}
// reading more bytes from tcp pipe of packetSize length
/*
Here it catches error as the packet size is incorrect but it throws error after receiving aroung 4-5K messages.
*/
completePacket := make([]byte, packetSize)
_, err = conn.Read(completePacket)
// checking error type
if err == io.EOF{
break
}
if err != nil{
break
}
fmt.Println(completePacket)
}
}