coredump when using 'Dry-run' with node_exporter_metrics input

[Elwell]

Bug Report

Describe the bug
'Dry-run' option (-D) causes coredump when used with node_exporter_metrics input

To Reproduce
fluent-bit -D -i node_exporter_metrics or a config file with

pipeline:
  inputs:
    - name: node_exporter_metrics
      tag: metrics_ne

leads to the following:

Fluent Bit v3.2.4
* Copyright (C) 2015-2024 The Fluent Bit Authors
* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
* https://fluentbit.io

______ _                  _    ______ _ _           _____  _____
|  ___| |                | |   | ___ (_) |         |____ |/ __  \
| |_  | |_   _  ___ _ __ | |_  | |_/ /_| |_  __   __   / /`' / /'
|  _| | | | | |/ _ \ '_ \| __| | ___ \ | __| \ \ / /   \ \  / /
| |   | | |_| |  __/ | | | |_  | |_/ / | |_   \ V /.___/ /./ /___
\_|   |_|\__,_|\___|_| |_|\__| \____/|_|\__|   \_/ \____(_)_____/


configuration test is successful
[2025/01/16 11:10:33] [engine] caught signal (SIGSEGV)
#0  0x52a9ee            in  ???() at ???:0
#1  0x544c9d            in  ???() at ???:0
#2  0x51f5b4            in  ???() at ???:0
#3  0x4912b9            in  ???() at ???:0
#4  0x7f30d68295cf      in  ???() at ???:0
#5  0x7f30d682967f      in  ???() at ???:0
#6  0x48ee54            in  ???() at ???:0
#7  0xffffffffffffffff  in  ???() at ???:0
Aborted (core dumped)
[root@ns4 fluent-bit]#

Expected behavior
just the 'configuration test is successful' and exit 0

Screenshots
N/A

Your Environment

• Version used: fluent-bit-3.2.4-1.x86_64 from your upstream repo
• Configuration: - see above
• Environment name and version (e.g. Kubernetes? What version?):
• Server type and version: VM, x86_64
• Operating System and version: Rocky 9
• Filters and plugins: just the node_exporter_metrics is enough to trigger

Additional context
Also reported on slack - https://fluent-all.slack.com/archives/C0CTQGHKJ/p1736903076450509 - as it was causing validation of configs to fail

[Elwell]

The following inputs also produce coredumps on dry-run:

• process_exporter_metrics
• kubernetes_events
• event_type

(tested by getting all the list of inputs from fluent-bit -h and running a simple loop via

 while read input ; do echo $input ;  /opt/fluent-bit/bin/fluent-bit -D -i $input ; done < fb_in

[patrick-stephens]

Repeatable with the containers too:

$ docker run --rm -it fluent/fluent-bit:3.2.4 -D -i node_exporter_metrics 
Fluent Bit v3.2.4
* Copyright (C) 2015-2024 The Fluent Bit Authors
* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
* https://fluentbit.io

______ _                  _    ______ _ _           _____  _____ 
|  ___| |                | |   | ___ (_) |         |____ |/ __  \
| |_  | |_   _  ___ _ __ | |_  | |_/ /_| |_  __   __   / /`' / /'
|  _| | | | | |/ _ \ '_ \| __| | ___ \ | __| \ \ / /   \ \  / /  
| |   | | |_| |  __/ | | | |_  | |_/ / | |_   \ V /.___/ /./ /___
\_|   |_|\__,_|\___|_| |_|\__| \____/|_|\__|   \_/ \____(_)_____/


configuration test is successful
[2025/01/16 09:45:33] [engine] caught signal (SIGSEGV)
#0  0xaaaadc3579ab      in  flb_input_exit_all() at src/flb_input.c:1353
#1  0xaaaadc36e1eb      in  flb_engine_shutdown() at src/flb_engine.c:1150
#2  0xaaaadc34c94f      in  flb_destroy() at src/flb_lib.c:240
#3  0xaaaadc2e163f      in  flb_main() at src/fluent-bit.c:1360
#4  0xffff93a7773f      in  ???() at ???:0
#5  0xffff93a77817      in  ???() at ???:0
#6  0xaaaadc2df36f      in  ???() at ???:0
#7  0xffffffffffffffff  in  ???() at ???:0