diff --git a/common/bufio/conn.go b/common/bufio/conn.go
index f30e089..b8a5c03 100644
--- a/common/bufio/conn.go
+++ b/common/bufio/conn.go
@@ -532,6 +532,7 @@ type ExtendedWriterWrapper struct {
 }
 
 func (w *ExtendedWriterWrapper) WriteBuffer(buffer *buf.Buffer) error {
+	defer buffer.Release()
 	return common.Error(w.Write(buffer.Bytes()))
 }
 
diff --git a/common/bufio/io.go b/common/bufio/io.go
index 217cc97..0dea32b 100644
--- a/common/bufio/io.go
+++ b/common/bufio/io.go
@@ -22,7 +22,6 @@ func ReadFrom(reader N.PacketReader, buffer *buf.Buffer) (n int, addr net.Addr,
 }
 
 func Write(writer N.ExtendedWriter, buffer *buf.Buffer) (n int, err error) {
-	defer buffer.Release()
 	dataLen := buffer.Len()
 	err = writer.WriteBuffer(buffer)
 	if err == nil {
@@ -32,7 +31,6 @@ func Write(writer N.ExtendedWriter, buffer *buf.Buffer) (n int, err error) {
 }
 
 func WriteTo(writer N.PacketWriter, buffer *buf.Buffer, addr net.Addr) (n int, err error) {
-	defer buffer.Release()
 	dataLen := buffer.Len()
 	err = writer.WritePacket(buffer, M.SocksaddrFromNet(addr))
 	if err == nil {
diff --git a/common/bufio/limit.go b/common/bufio/limit.go
deleted file mode 100644
index 98e3e42..0000000
--- a/common/bufio/limit.go
+++ /dev/null
@@ -1,50 +0,0 @@
-package bufio
-
-import (
-	"io"
-
-	"github.com/sagernet/sing/common"
-	"github.com/sagernet/sing/common/buf"
-	N "github.com/sagernet/sing/common/network"
-)
-
-type LimitedWriter struct {
-	upstream       N.ExtendedWriter
-	maxChunkLength int
-}
-
-func NewLimitedWriter(writer io.Writer, maxChunkLength int) *LimitedWriter {
-	return &LimitedWriter{
-		upstream:       NewExtendedWriter(writer),
-		maxChunkLength: maxChunkLength,
-	}
-}
-
-func (w *LimitedWriter) Write(p []byte) (n int, err error) {
-	for pLen := len(p); pLen > 0; {
-		var data []byte
-		if pLen > w.maxChunkLength {
-			data = p[:w.maxChunkLength]
-			p = p[w.maxChunkLength:]
-			pLen -= w.maxChunkLength
-		} else {
-			data = p
-			pLen = 0
-		}
-		var writeN int
-		writeN, err = w.upstream.Write(data)
-		if err != nil {
-			return
-		}
-		n += writeN
-	}
-	return
-}
-
-func (w *LimitedWriter) WriteBuffer(buffer *buf.Buffer) error {
-	if buffer.Len() <= w.maxChunkLength {
-		return w.upstream.WriteBuffer(buffer)
-	}
-	defer buffer.Release()
-	return common.Error(w.Write(buffer.Bytes()))
-}
diff --git a/common/bufio/once.go b/common/bufio/once.go
index 6e048d6..7c37e31 100644
--- a/common/bufio/once.go
+++ b/common/bufio/once.go
@@ -22,7 +22,7 @@ func CopyOnce(dst io.Writer, src io.Reader) (n int64, err error) {
 
 func CopyExtendedOnce(dst N.ExtendedWriter, src N.ExtendedReader) (n int64, err error) {
 	var buffer *buf.Buffer
-	if _, unsafe := common.Cast[N.ThreadUnsafeWriter](dst); unsafe {
+	if N.IsUnsafeWriter(dst) {
 		buffer = buf.New()
 	} else {
 		_buffer := buf.StackNew()
diff --git a/common/network/thread.go b/common/network/thread.go
index 3ef0e17..dca2073 100644
--- a/common/network/thread.go
+++ b/common/network/thread.go
@@ -22,6 +22,11 @@ type HeadroomWriter interface {
 	Headroom() int
 }
 
+func IsUnsafeWriter(writer any) bool {
+	_, isUnsafe := common.Cast[ThreadUnsafeWriter](writer)
+	return isUnsafe
+}
+
 func CalculateHeadroom(writer any) int {
 	var headroom int
 	if headroomWriter, needHeadroom := writer.(HeadroomWriter); needHeadroom {
diff --git a/common/uot/server.go b/common/uot/server.go
index efd0c6e..b8605bb 100644
--- a/common/uot/server.go
+++ b/common/uot/server.go
@@ -44,6 +44,7 @@ func (c *ServerConn) RemoteAddr() net.Addr {
 	return pipeAddr{}
 }
 
+//warn:unsafe
 func (c *ServerConn) loopInput() {
 	_buffer := buf.StackNew()
 	defer common.KeepAlive(_buffer)
@@ -79,6 +80,7 @@ func (c *ServerConn) loopInput() {
 	c.Close()
 }
 
+//warn:unsafe
 func (c *ServerConn) loopOutput() {
 	_buffer := buf.StackNew()
 	defer common.KeepAlive(_buffer)
diff --git a/go.mod b/go.mod
index 5e43a31..228feda 100644
--- a/go.mod
+++ b/go.mod
@@ -2,4 +2,4 @@ module github.com/sagernet/sing
 
 go 1.18
 
-require golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8
+require golang.org/x/sys v0.0.0-20220731174439-a90be440212d
diff --git a/go.sum b/go.sum
index 28ab7f7..b7c2d11 100644
--- a/go.sum
+++ b/go.sum
@@ -1,2 +1,2 @@
-golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 h1:0A+M6Uqn+Eje4kHMK80dtF3JCXC4ykBgQG4Fe06QRhQ=
-golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220731174439-a90be440212d h1:Sv5ogFZatcgIMMtBSTTAgMYsicp25MXBubjXNDKwm80=
+golang.org/x/sys v0.0.0-20220731174439-a90be440212d/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
diff --git a/protocol/http/handshake.go b/protocol/http/handshake.go
index 516e3be..1b59574 100644
--- a/protocol/http/handshake.go
+++ b/protocol/http/handshake.go
@@ -63,10 +63,7 @@ func HandleConnection(ctx context.Context, conn net.Conn, reader *std_bufio.Read
 
 			var requestConn net.Conn
 			if reader.Buffered() > 0 {
-				_buffer := buf.StackNewSize(reader.Buffered())
-				defer common.KeepAlive(_buffer)
-				buffer := common.Dup(_buffer)
-				defer buffer.Release()
+				buffer := buf.NewSize(reader.Buffered())
 				_, err = buffer.ReadFullFrom(reader, reader.Buffered())
 				if err != nil {
 					return err
diff --git a/protocol/socks/packet.go b/protocol/socks/packet.go
index c228c34..c95c164 100644
--- a/protocol/socks/packet.go
+++ b/protocol/socks/packet.go
@@ -43,6 +43,7 @@ func (c *AssociatePacketConn) RemoteAddr() net.Addr {
 	return c.addr
 }
 
+//warn:unsafe
 func (c *AssociatePacketConn) ReadFrom(p []byte) (n int, addr net.Addr, err error) {
 	buffer := buf.With(p)
 	n, _, err = bufio.ReadFrom(c.PacketConn, buffer)
@@ -59,6 +60,7 @@ func (c *AssociatePacketConn) ReadFrom(p []byte) (n int, addr net.Addr, err erro
 	return
 }
 
+//warn:unsafe
 func (c *AssociatePacketConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
 	destination := M.SocksaddrFromNet(addr)
 	_buffer := buf.StackNewSize(3 + M.SocksaddrSerializer.AddrPortLen(destination) + len(p))
@@ -98,7 +100,6 @@ func (c *AssociatePacketConn) ReadPacket(buffer *buf.Buffer) (M.Socksaddr, error
 }
 
 func (c *AssociatePacketConn) WritePacket(buffer *buf.Buffer, destination M.Socksaddr) error {
-	defer buffer.Release()
 	header := buf.With(buffer.ExtendHeader(3 + M.SocksaddrSerializer.AddrPortLen(destination)))
 	common.Must(header.WriteZeroN(3))
 	common.Must(M.SocksaddrSerializer.WriteAddrPort(header, destination))