events_enrich: do not try to close nil channel (#2000)

rafaeldtinoco · web-flow · commit 1cd5e6da6d88 · 2022-07-21T16:42:18.000-03:00
Fixes: #1999 Commit 9be596e ("enrich: fix lock in cleanup logic (cgroup_rmdir)...") added a channel closure for the cgroup_rmdir but, if container was started before tracee, the channel might not exist. Check for channel existance before closing it.
diff --git a/pkg/ebpf/events_enrich.go b/pkg/ebpf/events_enrich.go
@@ -109,13 +109,12 @@ func (t *Tracee) enrichContainerEvents(ctx gocontext.Context, in <-chan *trace.E
 								}
 							}
 						}
+						close(queues[cgroupId])
 					}
-					bLock.RUnlock()
-
+					bLock.RUnlock() // give de-queue events a chance
 					bLock.Lock()
 					delete(enrichDone, cgroupId)
 					delete(enrichInfo, cgroupId)
-					close(queues[cgroupId])
 					delete(queues, cgroupId)
 					bLock.Unlock()
 

Original file line number	Diff line number	Diff line change
`@@ -109,13 +109,12 @@ func (t Tracee) enrichContainerEvents(ctx gocontext.Context, in <-chan trace.E`
`109`	`109`	`}`
`110`	`110`	`}`
`111`	`111`	`}`
	`112`	`+ close(queues[cgroupId])`
`112`	`113`	`}`
`113`		`- bLock.RUnlock()`
`114`		`-`
	`114`	`+ bLock.RUnlock() // give de-queue events a chance`
`115`	`115`	`bLock.Lock()`
`116`	`116`	`delete(enrichDone, cgroupId)`
`117`	`117`	`delete(enrichInfo, cgroupId)`
`118`		`- close(queues[cgroupId])`
`119`	`118`	`delete(queues, cgroupId)`
`120`	`119`	`bLock.Unlock()`
`121`	`120`