crash while passing an empty parameter through chain of scl blocks

[furiel]

Dear maintainers, I noticed there is some kind of crash when I want to pass an "" parameter through multiple embedded scl blocks. Could you take a look?

Reproduction

@version: current

block destination second(...) {
      `__VARARGS__`
};

block destination first(...) {
      second(`__VARARGS__`);
};

log {
   destination{ first(some-param("")) };
};

Backtrace:

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7e4967b in _report_generator_args (key=0x5555556075b0, value=0x0, user_data=0x55555561dd40)
    at ../lib/cfg-block-generator.c:42
42	  for (const gchar *c = (const gchar *) value; *c; c++)
(gdb) bt
#0  0x00007ffff7e4967b in _report_generator_args (key=0x5555556075b0, value=0x0, user_data=0x55555561dd40)
    at ../lib/cfg-block-generator.c:42
#1  0x00007ffff74fb9bb in g_hash_table_foreach (hash_table=0x5555555b8420, 
    func=0x7ffff7e493f3 <_report_generator_args>, user_data=0x55555561dd40) at ../glib/glib/ghash.c:2117
#2  0x00007ffff7e484d3 in cfg_args_foreach (self=0x55555561dd80, func=0x7ffff7e493f3 <_report_generator_args>, 
    user_data=0x55555561dd40) at ../lib/cfg-args.c:53
#3  0x00007ffff7e497a8 in cfg_block_generator_generate (self=0x5555556099b0, cfg=0x555555584790, 
    args=0x55555561dd80, result=0x55555561dd40, reference=0x7fffffff99a0 "etc/syslog-ng.conf:8:7")
    at ../lib/cfg-block-generator.c:61
#4  0x00007ffff7e4c238 in cfg_lexer_parse_and_run_block_generator (self=0x55555560cb60, p=0x555555609a10, 
    yylval=0x7fffffff9d50) at ../lib/cfg-lexer.c:1083
#5  0x00007ffff7e4c4b5 in cfg_lexer_preprocess (self=0x55555560cb60, tok=10430, yylval=0x7fffffff9d50, 
    yylloc=0x7fffffff9d90) at ../lib/cfg-lexer.c:1151
#6  0x00007ffff7e4c693 in cfg_lexer_lex (self=0x55555560cb60, yylval=0x7fffffff9d50, yylloc=0x7fffffff9d90)
    at ../lib/cfg-lexer.c:1224
#7  0x00007ffff7e4e289 in main_lex (yylval=0x7fffffff9d50, yylloc=0x7fffffff9d90, lexer=0x55555560cb60)
    at ../lib/cfg-parser.c:233
#8  0x00007ffff7ea508f in main_parse (lexer=0x55555560cb60, dummy=0x7fffffffdaf8, arg=0x0) at lib/cfg-grammar.c:3867
#9  0x00007ffff7e4e521 in cfg_parser_parse (self=0x7ffff7fb6060 <main_parser>, lexer=0x55555560cb60, 
    instance=0x7fffffffdaf8, arg=0x0) at ../lib/cfg-parser.c:299
#10 0x00007ffff7e47a19 in cfg_run_parser (self=0x555555584790, lexer=0x55555560cb60, 
    parser=0x7ffff7fb6060 <main_parser>, result=0x7fffffffdaf8, arg=0x0) at ../lib/cfg.c:534
#11 0x00007ffff7e48039 in cfg_read_config (self=0x555555584790, fname=0x555555563320 "etc/syslog-ng.conf", 
    preprocess_into=0x0) at ../lib/cfg.c:655
#12 0x00007ffff7e71e43 in main_loop_read_and_init_config (self=0x7ffff7fba3c0 <main_loop>) at ../lib/mainloop.c:680
#13 0x0000555555556ac7 in main (argc=1, argv=0x7fffffffdcd8) at ../syslog-ng/main.c:319

[OverOrion]

Thank you for your report @furiel! I opened a PR with the potential fix.

[MrAnno]

Follow-up issue: #341