tracee: panic during initialization

[rafaeldtinoco]

Description

$ sudo ./dist/tracee --config ~/policies/config.yaml --policy ~/policies/network/ 
TIME             UID    COMM             PID     TID     RET              EVENT                     ARGS
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x110 pc=0x18506b8]

goroutine 28 [running]:
github.com/aquasecurity/tracee/pkg/ebpf.(*Tracee).enrichContainerEvents.func1()
        /home/rafaeldtinoco/work/ebpf/tracee-libbpfgo/pkg/ebpf/events_enrich.go:79 +0x128
created by github.com/aquasecurity/tracee/pkg/ebpf.(*Tracee).enrichContainerEvents
        /home/rafaeldtinoco/work/ebpf/tracee-libbpfgo/pkg/ebpf/events_enrich.go:73 +0x1f4

Output of tracee version:

v0.14.2-56-g234b9d0d

Output of uname -a:

Linux azure 6.3.2 #5 SMP Tue May 16 04:48:36 UTC 2023 aarch64 aarch64 aarch64 GNU/Linux

Additional details

[rafaeldtinoco]

Since our pipeline is (most of the times) a channel of pointers, those pointers could have been garbage collected, I believe, in case references to it don't matter any more (probably during our shutdown ?).

In the pipeline, the caching step checks if event is null before moving on in both 'in/out' channels.

I believe the same should happen in the enrich pipeline stage:

and any other stage.