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Previously, if the postmaster initialized OpenSSL's PRNG (which it will do when ssl=on in postgresql.conf), the same pseudo-random state would be inherited by each forked child process. The problem is masked to a considerable extent if the incoming connection uses SSL encryption, but when it does not, identical pseudo-random state is made available to functions like contrib/pgcrypto. The process's PID does get mixed into any requested random output, but on most systems that still only results in 32K or so distinct random sequences available across all Postgres sessions. This might allow an attacker who has database access to guess the results of "secure" operations happening in another session. To fix, forcibly reset the PRNG after fork(). Each child process that has need for random numbers from OpenSSL's generator will thereby be forced to go through OpenSSL's normal initialization sequence, which should provide much greater variability of the sequences. There are other ways we might do this that would be slightly cheaper, but this approach seems the most future-proof against SSL-related code changes. This has been assigned CVE-2013-1900, but since the issue and the patch have already been publicized on pgsql-hackers, there's no point in trying to hide this commit. Back-patch to all supported branches. Marko Kreen
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/.