Recognize terminated runsc gofers during teardown

patches/gvisor-9f8f6c917-gofer-zombie-state.patch

@@ -0,0 +1,82 @@
+diff --git a/runsc/container/container.go b/runsc/container/container.go
+index f0bfbf2..9fe6cf5 100644
+--- a/runsc/container/container.go
++++ b/runsc/container/container.go
+@@ -1321,6 +1321,14 @@ func (c *Container) waitForStopped() error {
+ 	defer cancel()
+ 	b := backoff.WithContext(backoff.NewConstantBackOff(100*time.Millisecond), ctx)
+ 	op := func() error {
++		stopped, err := processIsTerminal(goferPid)
++		if err != nil {
++			return err
++		}
++		if stopped {
++			c.GoferPid.Store(0)
++			return nil
++		}
+ 		if err := unix.Kill(goferPid, 0); err == nil {
+ 			return fmt.Errorf("gofer is still running")
+ 		}
+@@ -1330,6 +1338,25 @@ func (c *Container) waitForStopped() error {
+ 	return backoff.Retry(op, b)
+ }
+ 
++func processIsTerminal(pid int) (bool, error) {
++	status, err := os.ReadFile(fmt.Sprintf("/proc/%d/stat", pid))
++	if errors.Is(err, os.ErrNotExist) {
++		return true, nil
++	}
++	if err != nil {
++		return false, fmt.Errorf("reading process state: %v", err)
++	}
++	return processStateIsTerminal(status)
++}
++
++func processStateIsTerminal(status []byte) (bool, error) {
++	nameEnd := strings.LastIndexByte(string(status), ')')
++	if nameEnd < 0 || nameEnd+2 >= len(status) {
++		return false, fmt.Errorf("process state is malformed")
++	}
++	return status[nameEnd+2] == 'Z' || status[nameEnd+2] == 'X', nil
++}
++
+ // shouldCreateDeviceGofer indicates whether a device gofer connection should
+ // be created.
+ func shouldCreateDeviceGofer(spec *specs.Spec, conf *config.Config) bool {
+diff --git a/runsc/container/container_test.go b/runsc/container/container_test.go
+index 8b282c4..299745f 100644
+--- a/runsc/container/container_test.go
++++ b/runsc/container/container_test.go
+@@ -2965,6 +2965,32 @@ func TestGoferExits(t *testing.T) {
+ 	}
+ }
+ 
++func TestProcessStateIsTerminal(t *testing.T) {
++	tests := []struct {
++		name     string
++		status   string
++		terminal bool
++		valid    bool
++	}{
++		{name: "running", status: "123 (gofer) S 1", valid: true},
++		{name: "zombie", status: "123 (gofer) Z 1", terminal: true, valid: true},
++		{name: "dead", status: "123 (gofer) X 1", terminal: true, valid: true},
++		{name: "closing parenthesis in name", status: "123 (gofer)) Z 1", terminal: true, valid: true},
++		{name: "malformed", status: "123 gofer Z 1"},
++	}
++	for _, test := range tests {
++		t.Run(test.name, func(t *testing.T) {
++			terminal, err := processStateIsTerminal([]byte(test.status))
++			if (err == nil) != test.valid {
++				t.Fatalf("processStateIsTerminal() error = %v, want valid %t", err, test.valid)
++			}
++			if terminal != test.terminal {
++				t.Errorf("processStateIsTerminal() = %t, want %t", terminal, test.terminal)
++			}
++		})
++	}
++}
++
+ func TestRootNotMount(t *testing.T) {
+ 	appSym, err := testutil.FindFile("test/cmd/test_app/test_app")
+ 	if err != nil {