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pgstat_read_statsfile() has never checked that the kind of a hash entry is variable-sized. Since44539786b8, that has begun tracking which hash table a kind ID should use, it is possible to finish with a NULL pointer dereference for a PGSTAT_FILE_ENTRY_HASH. Fixed-sized stats kinds have no hash table and no DSA area, hence their dsa references in pgStatLocal.kind_hash[] are NULL. This case can occur when reading statistics files if the same kind ID is reused across server restarts, with shared_preload_libraries loading different stats kind information each time: stats written with a set of PGSTAT_FILE_ENTRY_HASH, then read back with the same kind ID pointing to a custom fixed-sized kind info. Oversight in44539786b8. Reported-by: Zsolt Parragi <zsolt.parragi@percona.com> Author: Sami Imseih <samimseih.pg@gmail.com> Author: Zsolt Parragi <zsolt.parragi@percona.com> Discussion: https://postgr.es/m/CAN4CZFMxuOOuYV14+i3YcPG-16q02eBtSVa82J111=ZnDwSicA@mail.gmail.com
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/.