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If we error out during execution of a SQL-language function, we will often leave behind non-null pointers in its SQLFunctionCache's cplan and eslist fields. This is problematic if the SQLFunctionCache is re-used, because those pointers will point at resources that were released during error cleanup. This problem escaped detection so far because ordinarily we won't re-use an FmgrInfo+SQLFunctionCache struct after a query error. However, in the rather improbable case that someone implements an opclass support function in SQL language, there will be long-lived FmgrInfos for it in the relcache, and then the problem is reachable after the function throws an error. To fix, add a flag to SQLFunctionCache that tracks whether execution escapes out of fmgr_sql, and clear out the relevant fields during init_sql_fcache if so. (This is going to need more thought if we ever try to share FMgrInfos across threads; but it's very far from being the only problem such a project will encounter, since many functions regard fn_extra as being query-local state.) This broke at commit 0313c5dc6; before that we did not try to re-use SQLFunctionCache state across calls. Hence, back-patch to v18. Bug: #19026 Reported-by: Alexander Lakhin <exclusion@gmail.com> Author: Tom Lane <tgl@sss.pgh.pa.us> Discussion: https://postgr.es/m/19026-90aed5e71d0c8af3@postgresql.org Backpatch-through: 18
PostgreSQL Database Management System
This directory contains the source code distribution of the PostgreSQL database management system.
PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.