50d6e533e4
FetchStatementTargetList() dereferenced the portal named by a FetchStmt without checking that it still exists. With the extended query protocol, a client can sent a Parse "FETCH n FROM c" while cursor "c" is open (which caches a result's TupleDesc), issue a CLOSE on cursor "c", and then Describe the prepared statement or a portal bound to it. Describe would re-resolve the target list through the named cursor, and crash. In a non-assert builds, this causes a NULL pointer dereference. An assertion was triggered in assert builds slightly before the pointer dereference. This commit changes the describe of a FetchStmt to match with the ExecuteStmt case: if the named cursor's portal is invalid, fail rather than assume that the portal should always exist. A test case is added to libpq_pipeline, backpatchable all the way down. Author: Dirkjan Bussink <d.bussink@gmail.com> Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us> Reviewed-by: Michael Paquier <michael@paquier.xyz> Discussion: https://postgr.es/m/7DE248EB-7509-4F8A-9F37-4694A40BBAB7@gmail.com Backpatch-through: 14
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/.