E.170.1. Migration to Version 7.4.29

A dump/restore is not required for those running 7.4.X. However, if you are upgrading from a version earlier than 7.4.26, see Section E.173.

E.170.2. Changes

• Enforce restrictions in plperl using an opmask applied to the whole interpreter, instead of using Safe.pm (Tim Bunce, Andrew Dunstan)

  Recent developments have convinced us that Safe.pm is too insecure to rely on for making plperl trustable. This change removes use of Safe.pm altogether, in favor of using a separate interpreter with an opcode mask that is always applied. Pleasant side effects of the change include that it is now possible to use Perl's strict pragma in a natural way in plperl, and that Perl's $a and $b variables work as expected in sort routines, and that function compilation is significantly faster. (CVE-2010-1169)

• Prevent PL/Tcl from executing untrustworthy code from pltcl_modules (Tom)

  PL/Tcl's feature for autoloading Tcl code from a database table could be exploited for trojan-horse attacks, because there was no restriction on who could create or insert into that table. This change disables the feature unless pltcl_modules is owned by a superuser. (However, the permissions on the table are not checked, so installations that really need a less-than-secure modules table can still grant suitable privileges to trusted non-superusers.) Also, prevent loading code into the unrestricted "normal" Tcl interpreter unless we are really going to execute a pltclu function. (CVE-2010-1170)

• Do not allow an unprivileged user to reset superuser-only parameter settings (Alvaro)

  Previously, if an unprivileged user ran ALTER USER ... RESET ALL for himself, or ALTER DATABASE ... RESET ALL for a database he owns, this would remove all special parameter settings for the user or database, even ones that are only supposed to be changeable by a superuser. Now, the ALTER will only remove the parameters that the user has permission to change.

• Avoid possible crash during backend shutdown if shutdown occurs when a CONTEXT addition would be made to log entries (Tom)

  In some cases the context-printing function would fail because the current transaction had already been rolled back when it came time to print a log message.

• Update pl/perl's ppport.h for modern Perl versions (Andrew)

• Fix assorted memory leaks in pl/python (Andreas Freund, Tom)

• Ensure that contrib/pgstattuple functions respond to cancel interrupts promptly (Tatsuhito Kasahara)

• Make server startup deal properly with the case that shmget() returns EINVAL for an existing shared memory segment (Tom)

  This behavior has been observed on BSD-derived kernels including OS X. It resulted in an entirely-misleading startup failure complaining that the shared memory request size was too large.