Segv from simple wildcard

[mnp]

Bug Report

Describe the bug
SIGSEGV

To Reproduce

$ docker run -v `pwd`:/foo --rm -it fluent/fluent-bit -c /foo/conf
Fluent Bit v2.1.2
* Copyright (C) 2015-2022 The Fluent Bit Authors
* Fluent Bit is a CNCF sub-project under the umbrella of Fluentd
* https://fluentbit.io

[2023/05/12 01:28:53] [ info] [fluent bit] version=2.1.2, commit=113c7c00d2, pid=1
[2023/05/12 01:28:53] [ info] [storage] ver=1.4.0, type=memory, sync=normal, checksum=off, max_chunks_up=128
[2023/05/12 01:28:53] [ info] [cmetrics] version=0.6.1
[2023/05/12 01:28:53] [ info] [ctraces ] version=0.3.0
[2023/05/12 01:28:53] [ info] [input:dummy:dummy.0] initializing
[2023/05/12 01:28:53] [ info] [input:dummy:dummy.0] storage_strategy='memory' (memory only)
ret=-113. start=*s3 end=
ret=-113. start=*s3 end=
[2023/05/12 01:28:53] [debug] [filter:modify:modify.0] Initialized modify filter with 0 conditions and 1 rules
[2023/05/12 01:28:53] [ info] [sp] stream processor started
[2023/05/12 01:28:53] [ info] [output:stdout:stdout.0] worker #0 started
[2023/05/12 01:28:55] [ warn] [engine] service will shutdown in max 2 seconds
[2023/05/12 01:28:55] [ info] [input] pausing dummy.0
[0] dummy.0: [[1683854934.165236446, {}], {"r1"=>"someval", "s1"=>{"s2"=>nil, "s3"=>nil}, "r2"=>{"x"=>0}}]
[2023/05/12 01:28:56] [ info] [engine] service has stopped (0 pending tasks)
[2023/05/12 01:28:56] [ info] [input] pausing dummy.0
[2023/05/12 01:28:56] [engine] caught signal (SIGSEGV)
#0  0x5599036f4623      in  flb_regex_destroy() at src/flb_regex.c:312
#1  0x559903b2f227      in  teardown() at plugins/filter_modify/modify.c:82
#2  0x559903b3419c      in  cb_modify_exit() at plugins/filter_modify/modify.c:1531
#3  0x559903642f90      in  flb_filter_instance_exit() at src/flb_filter.c:352
#4  0x559903642ff6      in  flb_filter_exit() at src/flb_filter.c:370
#5  0x55990366f1f6      in  flb_engine_shutdown() at src/flb_engine.c:1046
#6  0x55990366ee62      in  flb_engine_start() at src/flb_engine.c:942
#7  0x559903613531      in  flb_lib_worker() at src/flb_lib.c:638
#8  0x7f94f304bea6      in  ???() at ???:0
#9  0x7f94f28fea2e      in  ???() at ???:0
#10 0xffffffffffffffff  in  ???() at ???:0

• Steps to reproduce the problem:

Expected behavior
Print an error saying what I did wrong and continue.

Your Environment

• Version used: docker x86 v2.1.2
• Configuration:

[SERVICE]
    Flush      1
    Grace      2
    Log_Level  info

[INPUT]
    Name       dummy
    Dummy      {"r1": "someval", "s1": {"s2": null, "s3": null}, "r2": {"x": 0}}
    Samples    1

[FILTER]
    Name                 modify
    Match                *
    Log_Level            debug
    Remove_wildcard      *s3

[OUTPUT]
    Name  stdout
    Match *

[OUTPUT]
    Name exit
    Match *

Additional context
I suspect it's the bad wildcard.

[leonardo-albertovich]

The problem is that the filters initialization routine has a few flaws :

1. The regex compilation results are not checked and thus an invalid regex will just leave an invalid value (NULL) in place which will be later on used and I suspect that wouldn't go well. << this is NOT your case
2. The teardown routine unconditionally tries to dispose of all the rule components without checking their state (ie. a regex field wasn't or couldn't be initialized).

Would you like to take a stab at fixing it? I can't give you an ETA for the fix but I can provide any assistance you might need if you try to contribute a patch.

Thanks for reporting this issue.

[nokute78]

I sent a patch #7378