5 files changed, 33 insertions, 22 deletions
diff --git a/pkg/tcpip/network/ipv4/icmp.go b/pkg/tcpip/network/ipv4/icmp.go
index f663fdc0b..3f2093f00 100644
--- a/pkg/tcpip/network/ipv4/icmp.go
+++ b/pkg/tcpip/network/ipv4/icmp.go
@@ -163,10 +163,12 @@ func (e *endpoint) handleControl(errInfo stack.TransportError, pkt *stack.Packet
 		return
 	}
 
-	// Skip the ip header, then deliver the error.
-	pkt.Data().TrimFront(hlen)
+	// Keep needed information before trimming header.
 	p := hdr.TransportProtocol()
-	e.dispatcher.DeliverTransportError(srcAddr, hdr.DestinationAddress(), ProtocolNumber, p, errInfo, pkt)
+	dstAddr := hdr.DestinationAddress()
+	// Skip the ip header, then deliver the error.
+	pkt.Data().DeleteFront(hlen)
+	e.dispatcher.DeliverTransportError(srcAddr, dstAddr, ProtocolNumber, p, errInfo, pkt)
 }
 
 func (e *endpoint) handleICMP(pkt *stack.PacketBuffer) {
@@ -336,14 +338,16 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer) {
 	case header.ICMPv4DstUnreachable:
 		received.dstUnreachable.Increment()
 
-		pkt.Data().TrimFront(header.ICMPv4MinimumSize)
-		switch h.Code() {
+		mtu := h.MTU()
+		code := h.Code()
+		pkt.Data().DeleteFront(header.ICMPv4MinimumSize)
+		switch code {
 		case header.ICMPv4HostUnreachable:
 			e.handleControl(&icmpv4DestinationHostUnreachableSockError{}, pkt)
 		case header.ICMPv4PortUnreachable:
 			e.handleControl(&icmpv4DestinationPortUnreachableSockError{}, pkt)
 		case header.ICMPv4FragmentationNeeded:
-			networkMTU, err := calculateNetworkMTU(uint32(h.MTU()), header.IPv4MinimumSize)
+			networkMTU, err := calculateNetworkMTU(uint32(mtu), header.IPv4MinimumSize)
 			if err != nil {
 				networkMTU = 0
 			}
diff --git a/pkg/tcpip/network/ipv6/icmp.go b/pkg/tcpip/network/ipv6/icmp.go
index 1319db32b..28bb61a08 100644
--- a/pkg/tcpip/network/ipv6/icmp.go
+++ b/pkg/tcpip/network/ipv6/icmp.go
@@ -181,10 +181,13 @@ func (e *endpoint) handleControl(transErr stack.TransportError, pkt *stack.Packe
 		return
 	}
 
+	// Keep needed information before trimming header.
+	p := hdr.TransportProtocol()
+	dstAddr := hdr.DestinationAddress()
+
 	// Skip the IP header, then handle the fragmentation header if there
 	// is one.
-	pkt.Data().TrimFront(header.IPv6MinimumSize)
-	p := hdr.TransportProtocol()
+	pkt.Data().DeleteFront(header.IPv6MinimumSize)
 	if p == header.IPv6FragmentHeader {
 		f, ok := pkt.Data().PullUp(header.IPv6FragmentHeaderSize)
 		if !ok {
@@ -196,14 +199,14 @@ func (e *endpoint) handleControl(transErr stack.TransportError, pkt *stack.Packe
 			// because they don't have the transport headers.
 			return
 		}
+		p = fragHdr.TransportProtocol()
 
 		// Skip fragmentation header and find out the actual protocol
 		// number.
-		pkt.Data().TrimFront(header.IPv6FragmentHeaderSize)
-		p = fragHdr.TransportProtocol()
+		pkt.Data().DeleteFront(header.IPv6FragmentHeaderSize)
 	}
 
-	e.dispatcher.DeliverTransportError(srcAddr, hdr.DestinationAddress(), ProtocolNumber, p, transErr, pkt)
+	e.dispatcher.DeliverTransportError(srcAddr, dstAddr, ProtocolNumber, p, transErr, pkt)
 }
 
 // getLinkAddrOption searches NDP options for a given link address option using
@@ -327,11 +330,11 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, r
 			received.invalid.Increment()
 			return
 		}
-		pkt.Data().TrimFront(header.ICMPv6PacketTooBigMinimumSize)
 		networkMTU, err := calculateNetworkMTU(header.ICMPv6(hdr).MTU(), header.IPv6MinimumSize)
 		if err != nil {
 			networkMTU = 0
 		}
+		pkt.Data().DeleteFront(header.ICMPv6PacketTooBigMinimumSize)
 		e.handleControl(&icmpv6PacketTooBigSockError{mtu: networkMTU}, pkt)
 
 	case header.ICMPv6DstUnreachable:
@@ -341,8 +344,9 @@ func (e *endpoint) handleICMP(pkt *stack.PacketBuffer, hasFragmentHeader bool, r
 			received.invalid.Increment()
 			return
 		}
-		pkt.Data().TrimFront(header.ICMPv6DstUnreachableMinimumSize)
-		switch header.ICMPv6(hdr).Code() {
+		code := header.ICMPv6(hdr).Code()
+		pkt.Data().DeleteFront(header.ICMPv6DstUnreachableMinimumSize)
+		switch code {
 		case header.ICMPv6NetworkUnreachable:
 			e.handleControl(&icmpv6DestinationNetworkUnreachableSockError{}, pkt)
 		case header.ICMPv6PortUnreachable:
diff --git a/pkg/tcpip/stack/packet_buffer.go b/pkg/tcpip/stack/packet_buffer.go
index 646979d1e..9527416cf 100644
--- a/pkg/tcpip/stack/packet_buffer.go
+++ b/pkg/tcpip/stack/packet_buffer.go
@@ -364,9 +364,10 @@ func (d PacketData) PullUp(size int) (buffer.View, bool) {
 	return d.pk.data.PullUp(size)
 }
 
-// TrimFront removes count from the beginning of d. It panics if count >
-// d.Size().
-func (d PacketData) TrimFront(count int) {
+// DeleteFront removes count from the beginning of d. It panics if count >
+// d.Size(). All backing storage references after the front of the d are
+// invalidated.
+func (d PacketData) DeleteFront(count int) {
 	d.pk.data.TrimFront(count)
 }
 
diff --git a/pkg/tcpip/stack/packet_buffer_test.go b/pkg/tcpip/stack/packet_buffer_test.go
index 6728370c3..a794065d1 100644
--- a/pkg/tcpip/stack/packet_buffer_test.go
+++ b/pkg/tcpip/stack/packet_buffer_test.go
@@ -397,11 +397,11 @@ func TestPacketBufferData(t *testing.T) {
 				}
 			})
 
-			// TrimFront
+			// DeleteFront
 			for _, n := range []int{1, len(tc.data)} {
-				t.Run(fmt.Sprintf("TrimFront%d", n), func(t *testing.T) {
+				t.Run(fmt.Sprintf("DeleteFront%d", n), func(t *testing.T) {
 					pkt := tc.makePkt(t)
-					pkt.Data().TrimFront(n)
+					pkt.Data().DeleteFront(n)
 
 					checkData(t, pkt, []byte(tc.data)[n:])
 				})
diff --git a/pkg/tcpip/stack/stack_test.go b/pkg/tcpip/stack/stack_test.go
index 8ead3b8df..4fe9df999 100644
--- a/pkg/tcpip/stack/stack_test.go
+++ b/pkg/tcpip/stack/stack_test.go
@@ -138,11 +138,13 @@ func (f *fakeNetworkEndpoint) HandlePacket(pkt *stack.PacketBuffer) {
 
 	// Handle control packets.
 	if netHdr[protocolNumberOffset] == uint8(fakeControlProtocol) {
-		nb, ok := pkt.Data().PullUp(fakeNetHeaderLen)
+		hdr, ok := pkt.Data().PullUp(fakeNetHeaderLen)
 		if !ok {
 			return
 		}
-		pkt.Data().TrimFront(fakeNetHeaderLen)
+		// DeleteFront invalidates slices. Make a copy before trimming.
+		nb := append([]byte(nil), hdr...)
+		pkt.Data().DeleteFront(fakeNetHeaderLen)
 		f.dispatcher.DeliverTransportError(
 			tcpip.Address(nb[srcAddrOffset:srcAddrOffset+1]),
 			tcpip.Address(nb[dstAddrOffset:dstAddrOffset+1]),