sentry: save copy of tcp segment's delivered views to avoid in-struct pointers.

PiperOrigin-RevId: 224033238
Change-Id: Ie5b1854b29340843b02c123766d290a8738d7631

pkg/state/encode.go

@@ -119,9 +119,10 @@ func (es *encodeState) register(obj reflect.Value) uint64 {
 		if size := typ.Size(); size > 0 {
 			r := addrRange{addr, addr + size}
 			if !es.values.IsEmptyRange(r) {
-				panic(fmt.Errorf("overlapping objects: [new object] %#v [existing object] %#v", obj.Interface(), es.values.FindSegment(addr).Value().Elem().Interface()))
+				old := es.values.LowerBoundSegment(addr).Value().Interface().(recoverable)
+				panic(fmt.Errorf("overlapping objects: [new object] %#v [existing object path] %s", obj.Interface(), old.path()))
 			}
-			es.values.Add(r, obj)
+			es.values.Add(r, reflect.ValueOf(es.recoverable.copy()))
 		}
 	} else {
 		// Push back the map itself; when maps are encoded from the

pkg/tcpip/transport/tcp/segment.go

@@ -46,7 +46,7 @@ type segment struct {
 	data   buffer.VectorisedView     `state:".(buffer.VectorisedView)"`
 	// views is used as buffer for data when its length is large
 	// enough to store a VectorisedView.
-	views [8]buffer.View
+	views [8]buffer.View `state:"nosave"`
 	// viewToDeliver keeps track of the next View that should be
 	// delivered by the Read endpoint.
 	viewToDeliver  int

pkg/tcpip/transport/tcp/segment_state.go

@@ -22,7 +22,16 @@ import (
 func (s *segment) saveData() buffer.VectorisedView {
 	// We cannot save s.data directly as s.data.views may alias to s.views,
 	// which is not allowed by state framework (in-struct pointer).
-	return s.data.Clone(nil)
+	v := make([]buffer.View, len(s.data.Views()))
+	// For views already delivered, we cannot save them directly as they may
+	// have already been sliced and saved elsewhere (e.g., readViews).
+	for i := 0; i < s.viewToDeliver; i++ {
+		v[i] = append([]byte(nil), s.data.Views()[i]...)
+	}
+	for i := s.viewToDeliver; i < len(v); i++ {
+		v[i] = s.data.Views()[i]
+	}
+	return buffer.NewVectorisedView(s.data.Size(), v)
 }
 
 // loadData is invoked by stateify.