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. 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. I attached a bugfix for PG 15. Best regards, Karina Litskevich Postgres Professional: http://postgrespro.com/
From 5f0e59b225ebb408a0c971bc78e22050b296ae9a Mon Sep 17 00:00:00 2001 From: Karina Litskevich <litskevichkar...@gmail.com> Date: Thu, 6 Jul 2023 11:00:36 +0300 Subject: [PATCH v1] Fix MarkGUCPrefixReserved() to check all options --- src/backend/utils/misc/guc.c | 1 + 1 file changed, 1 insertion(+) diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index 915f557c68..c410ba532d 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -9723,6 +9723,7 @@ MarkGUCPrefixReserved(const char *className) num_guc_variables--; memmove(&guc_variables[i], &guc_variables[i + 1], (num_guc_variables - i) * sizeof(struct config_generic *)); + i--; } } -- 2.25.1
