cgroups/fs: fix NPE on Destroy than no cgroups are set

Denys Smirnov · Denys Smirnov · commit 3d26fc3fd7df · 2018-03-06T23:31:31.000+01:00
Currently Manager accepts nil cgroups when calling Apply, but it will panic then trying to call Destroy with the same config.

Signed-off-by: Denys Smirnov &lt;denys@sourced.tech&gt;
diff --git a/libcontainer/cgroups/fs/apply_raw.go b/libcontainer/cgroups/fs/apply_raw.go
@@ -161,7 +161,7 @@ func (m *Manager) Apply(pid int) (err error) {
 }
 
 func (m *Manager) Destroy() error {
-	if m.Cgroups.Paths != nil {
+	if m.Cgroups == nil || m.Cgroups.Paths != nil {
 		return nil
 	}
 	m.mu.Lock()

Original file line number	Diff line number	Diff line change
`@@ -161,7 +161,7 @@ func (m *Manager) Apply(pid int) (err error) {`
`161`	`161`	`}`
`162`	`162`
`163`	`163`	`func (m *Manager) Destroy() error {`
`164`		`- if m.Cgroups.Paths != nil {`
	`164`	`+ if m.Cgroups == nil \|\| m.Cgroups.Paths != nil {`
`165`	`165`	`return nil`
`166`	`166`	`}`
`167`	`167`	`m.mu.Lock()`