On 06/07/2023 12:17, Karina Litskevich wrote:
Hi hackers,
Ekaterina Sokolova and I have found a bug in PG 15. Since 88103567cb
MarkGUCPrefixReserved() is supposed not only reporting GUCs that
haven't been defined by the extension, but also removing them.
However, it removes them in a wrong way, so that a GUC that goes
after the removed GUC is never checked.
To reproduce the bug add the following to the postgresql.conf
shared_preload_libraries = 'pg_stat_statements'
pg_stat_statements.nonexisting_option_1 = on
pg_stat_statements.nonexisting_option_2 = on
pg_stat_statements.nonexisting_option_3 = on
pg_stat_statements.nonexisting_option_4 = on
and start the server. In the logfile you'll see only first and third
options reported invalid and removed.
Good catch!
In master MarkGUCPrefixReserved() iterates a hash table, not an array
as in PG 15. I'm not sure whether it is safe to remove an entry from
this hash table while iterating it, but at least I can't reproduce
the bug on master.
Yes, it's safe to remove the current element, while scanning a hash
table with hash_seq_init/search. See comment on hash_seq_init.
I attached a bugfix for PG 15.
Applied, thanks!
--
Heikki Linnakangas
Neon (https://neon.tech)
