3836d4b643
Whether from size overflow in gistSplit or from secondary splits, picksplit is (rarely) called with exactly two items to split. Formerly, due to special-case handling of the last item, this would lead to access to an uninitialized cache entry; prior to PG 13 this might have been harmless or at worst led to an incorrect union datum, but in 13 onwards it can cause a backend crash from using an uninitialized pointer. Repair by removing the special case, which was deemed not to have been appropriate anyway. Backpatch all the way, because this bug has existed since pg_trgm was added. Per report on IRC from user "ftzdomino". Analysis and testing by me, patch from Alexander Korotkov. Discussion: https://postgr.es/m/87k0usfdxg.fsf@news-spur.riddles.org.uk
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. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download/ See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.