Merge pull request #5168 from cyphar/1.4-5009-close-fd-on-error

[1.4] Close fds on error

libcontainer/init_linux.go

@@ -175,6 +175,7 @@ func startInitialization() (retErr error) {
 		return fmt.Errorf("unable to convert _LIBCONTAINER_LOGPIPE: %w", err)
 	}
 	logPipe := os.NewFile(uintptr(logFd), "logpipe")
+	defer logPipe.Close()
 
 	logrus.SetOutput(logPipe)
 	logrus.SetFormatter(new(logrus.JSONFormatter))
@@ -190,6 +191,7 @@ func startInitialization() (retErr error) {
 			return fmt.Errorf("unable to convert _LIBCONTAINER_FIFOFD: %w", err)
 		}
 		fifoFile = os.NewFile(uintptr(fifoFd), "initfifo")
+		defer fifoFile.Close()
 	}
 
 	var consoleSocket *os.File

libcontainer/mount_linux.go

@@ -250,7 +250,7 @@ func syscallMode(i fs.FileMode) (o uint32) {
 // process will need to do an old-fashioned mount(2) themselves.
 //
 // This helper is only intended to be used by goCreateMountSources.
-func mountFd(nsHandles *userns.Handles, m *configs.Mount) (*mountSource, error) {
+func mountFd(nsHandles *userns.Handles, m *configs.Mount) (_ *mountSource, retErr error) {
 	if !m.IsBind() {
 		return nil, errors.New("new mount api: only bind-mounts are supported")
 	}
@@ -261,6 +261,11 @@ func mountFd(nsHandles *userns.Handles, m *configs.Mount) (*mountSource, error)
 
 	var mountFile *os.File
 	var sourceType mountSourceType
+	defer func() {
+		if retErr != nil && mountFile != nil {
+			mountFile.Close()
+		}
+	}()
 
 	// Ideally, we would use OPEN_TREE_CLONE for everything, because we can
 	// be sure that the file descriptor cannot be used to escape outside of

libcontainer/process_linux.go

@@ -70,7 +70,7 @@ type processComm struct {
 	logPipeChild  *os.File
 }
 
-func newProcessComm() (*processComm, error) {
+func newProcessComm() (_ *processComm, retErr error) {
 	var (
 		comm processComm
 		err  error
@@ -79,10 +79,24 @@ func newProcessComm() (*processComm, error) {
 	if err != nil {
 		return nil, fmt.Errorf("unable to create init pipe: %w", err)
 	}
+	defer func() {
+		if retErr != nil {
+			comm.initSockParent.Close()
+			comm.initSockChild.Close()
+		}
+	}()
+
 	comm.syncSockParent, comm.syncSockChild, err = newSyncSockpair("sync")
 	if err != nil {
 		return nil, fmt.Errorf("unable to create sync pipe: %w", err)
 	}
+	defer func() {
+		if retErr != nil {
+			comm.syncSockParent.Close()
+			comm.syncSockChild.Close()
+		}
+	}()
+
 	comm.logPipeParent, comm.logPipeChild, err = os.Pipe()
 	if err != nil {
 		return nil, fmt.Errorf("unable to create log pipe: %w", err)

notify_socket.go

@@ -175,12 +175,18 @@ func notifyHost(client *net.UnixConn, ready []byte, pid1 int) error {
 var errUnexpectedRead = errors.New("unexpected read from synchronization pipe")
 
 // sdNotifyBarrier performs synchronization with systemd by means of the sd_notify_barrier protocol.
-func sdNotifyBarrier(client *net.UnixConn) error {
+func sdNotifyBarrier(client *net.UnixConn) (retErr error) {
 	// Create a pipe for communicating with systemd daemon.
 	pipeR, pipeW, err := os.Pipe()
 	if err != nil {
 		return err
 	}
+	defer func() {
+		if retErr != nil {
+			pipeW.Close()
+			pipeR.Close()
+		}
+	}()
 
 	// Get the FD for the unix socket file to be able to use sendmsg.
 	clientFd, err := client.File()