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In tuplesort.c:inittapes(), we calculate tapeSpace by first figuring out how many 'tapes' we can use (maxTapes) and then multiplying the result by the tape buffer overhead for each. Unfortunately, when we are on a system with an 8-byte long, we allow work_mem to be larger than 2GB and that allows maxTapes to be large enough that the 32bit arithmetic can overflow when multiplied against the buffer overhead. When this overflow happens, we end up adding the overflow to the amount of space available, causing the amount of memory allocated to be larger than work_mem. Note that to reach this point, you have to set work mem to at least 24GB and be sorting a set which is at least that size. Given that a user who can set work_mem to 24GB could also set it even higher, if they were looking to run the system out of memory, this isn't considered a security issue. This overflow risk was found by the Coverity scanner. Back-patch to all supported branches, as this issue has existed since before 8.4.
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: http://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. Changes between all PostgreSQL releases are recorded in the file HISTORY. 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 http://www.postgresql.org/download/. For more information look at our web site located at http://www.postgresql.org/.