Merge pull request #20647 from coolljt0725/fix_20638

Fix exec start api with detach and AttachStdin at same time. fixes #2…
Upstream-commit: cee4ff1c4ac0bb47ed847f3bb725fd6233613937
Component: engine

components/engine/daemon/exec.go

@@ -157,7 +157,7 @@ func (d *Daemon) ContainerExecStart(name string, stdin io.ReadCloser, stdout io.
 	logrus.Debugf("starting exec command %s in container %s", ec.ID, c.ID)
 	d.LogContainerEvent(c, "exec_start: "+ec.ProcessConfig.Entrypoint+" "+strings.Join(ec.ProcessConfig.Arguments, " "))
 
-	if ec.OpenStdin {
+	if ec.OpenStdin && stdin != nil {
 		r, w := io.Pipe()
 		go func() {
 			defer w.Close()