Prevent using zero as NICID.

PiperOrigin-RevId: 629890469

pkg/tcpip/errors.go

@@ -274,6 +274,19 @@ func (*ErrDuplicateNICID) IgnoreStats() bool {
 }
 func (*ErrDuplicateNICID) String() string { return "duplicate nic id" }
 
+// ErrInvalidNICID indicates the operation used an invalid NIC ID.
+//
+// +stateify savable
+type ErrInvalidNICID struct{}
+
+func (*ErrInvalidNICID) isError() {}
+
+// IgnoreStats implements Error.
+func (*ErrInvalidNICID) IgnoreStats() bool {
+	return false
+}
+func (*ErrInvalidNICID) String() string { return "invalid nic id" }
+
 // ErrInvalidEndpointState indicates the endpoint is in an invalid state.
 //
 // +stateify savable

pkg/tcpip/stack/stack.go

@@ -846,6 +846,9 @@ func (s *Stack) CreateNICWithOptions(id tcpip.NICID, ep LinkEndpoint, opts NICOp
 	s.mu.Lock()
 	defer s.mu.Unlock()
 
+	if id == 0 {
+		return &tcpip.ErrInvalidNICID{}
+	}
 	// Make sure id is unique.
 	if _, ok := s.nics[id]; ok {
 		return &tcpip.ErrDuplicateNICID{}

pkg/tcpip/stack/stack_test.go

@@ -2446,6 +2446,16 @@ func TestCreateNICWithOptions(t *testing.T) {
 		desc  string
 		calls []callArgsAndExpect
 	}{
+		{
+			desc: "InvalidNICID",
+			calls: []callArgsAndExpect{
+				{
+					nicID: tcpip.NICID(0),
+					opts:  stack.NICOptions{Name: "eth0"},
+					err:   &tcpip.ErrInvalidNICID{},
+				},
+			},
+		},
 		{
 			desc: "DuplicateNICID",
 			calls: []callArgsAndExpect{
@@ -2544,7 +2554,7 @@ func TestNICStats(t *testing.T) {
 
 	var txBytesTotal, rxBytesTotal, txPacketsTotal, rxPacketsTotal int
 	for i, nic := range nics {
-		nicid := tcpip.NICID(i)
+		nicid := tcpip.NICID(i + 1)
 		ep := channel.New(1, defaultMTU, "")
 		if err := s.CreateNIC(nicid, ep); err != nil {
 			t.Fatal("CreateNIC failed: ", err)