fix: ensure proper buffer reuse with pointer handling in sync.Pool

session/forwarder/forwarder.go

@@ -46,16 +46,17 @@ func New(config config.Config, slug slug.Slug, conn ssh.Conn) Forwarder {
 		bufferPool: sync.Pool{
 			New: func() interface{} {
 				bufSize := config.BufferSize()
-				return make([]byte, bufSize)
+				buf := make([]byte, bufSize)
+				return &buf
 			},
 		},
 	}
 }
 
 func (f *forwarder) copyWithBuffer(dst io.Writer, src io.Reader) (written int64, err error) {
-	buf := f.bufferPool.Get().([]byte)
+	buf := f.bufferPool.Get().(*[]byte)
 	defer f.bufferPool.Put(buf)
-	return io.CopyBuffer(dst, src, buf)
+	return io.CopyBuffer(dst, src, *buf)
 }
 
 func (f *forwarder) OpenForwardedChannel(ctx context.Context, origin net.Addr) (ssh.Channel, <-chan *ssh.Request, error) {

session/forwarder/forwarder_test.go

@@ -273,8 +273,8 @@ func TestNew(t *testing.T) {
 
 			forwarder := New(cfg, s, conn).(*forwarder)
 
-			buf := forwarder.bufferPool.Get().([]byte)
-			require.Len(t, buf, tt.wantBufLen)
+			buf := forwarder.bufferPool.Get().(*[]byte)
+			require.Len(t, *buf, tt.wantBufLen)
 			forwarder.bufferPool.Put(buf)
 
 			assert.Equal(t, types.TunnelTypeUNKNOWN, forwarder.TunnelType())
@@ -1082,8 +1082,9 @@ func TestCopyWithBufferReusesBuffer(t *testing.T) {
 	cfg.On("BufferSize").Return(16).Maybe()
 	forwarder := New(cfg, slug.New(), nil).(*forwarder)
 
-	buf1 := forwarder.bufferPool.Get().([]byte)
-	initialPtr := &buf1[0]
+	buf1 := forwarder.bufferPool.Get().(*[]byte)
+	initialPtr := buf1
+
 	forwarder.bufferPool.Put(buf1)
 
 	src := io.NopCloser(bytes.NewReader([]byte("test")))
@@ -1091,16 +1092,19 @@ func TestCopyWithBufferReusesBuffer(t *testing.T) {
 	_, err := forwarder.copyWithBuffer(dst, src)
 	require.NoError(t, err)
 
-	buf2 := forwarder.bufferPool.Get().([]byte)
-	secondPtr := &buf2[0]
+	buf2 := forwarder.bufferPool.Get().(*[]byte)
+	secondPtr := buf2
+
 	forwarder.bufferPool.Put(buf2)
 
-	assert.Equal(t, len(buf1), len(buf2))
+	assert.Equal(t, initialPtr, secondPtr, "Buffers should be the same pointer")
 
-	assert.Len(t, buf2, 16)
+	assert.Len(t, *buf2, 16)
+	assert.Len(t, *buf1, 16)
 
 	_ = initialPtr
 	_ = secondPtr
+
 	cfg.AssertExpectations(t)
 }