fix possible memory confusion in unsafe slice cast

Author: jlauinger

utils.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"reflect"
+	"runtime"
 	"strconv"
 	"strings"
 	"time"
@@ -256,7 +257,12 @@ func strCmp(s1, s2 string) int {
 }
 
 func unsafeFastStringToReadOnlyBytes(s string) []byte {
+	b := make([]byte, 0)
 	sh := (*reflect.StringHeader)(unsafe.Pointer(&s))
-	bh := reflect.SliceHeader{Data: sh.Data, Len: sh.Len, Cap: sh.Len}
-	return *(*[]byte)(unsafe.Pointer(&bh))
+	bh := (*reflect.SliceHeader)(unsafe.Pointer(&b))
+	bh.Data = sh.Data
+	bh.Cap = sh.Len
+	bh.Len = sh.Len
+	runtime.KeepAlive(s)
+	return b
 }