Due to simplistic quoting and confusion of database names with conninfo
strings, roles with the CREATEDB or CREATEROLE option could escalate to
superuser privileges when a superuser next ran certain maintenance
commands. The new coding rule for PQconnectdbParams() calls, documented
at conninfo_array_parse(), is to pass expand_dbname=true and wrap
literal database names in a trivial connection string. Escape
zero-length values in appendConnStrVal(). Back-patch to 9.1 (all
supported versions).
Nathan Bossart, Michael Paquier, and Noah Misch. Reviewed by Peter
Eisentraut. Reported by Nathan Bossart.
Security: CVE-2016-5424
Don't insist on pg_dumpall and psql being present in the old cluster,
since they are not needed. Do insist on pg_resetxlog being present
(in both old and new), since we need it. Also check for pg_config,
but only in the new cluster. Remove the useless attempt to call
pg_config in the old cluster; we don't need to know the old value of
--pkglibdir. (In the case of a stripped-down migration installation
there might be nothing there to look at anyway, so any future change
that might reintroduce that need would have to be considered carefully.)
Per my attempts to build a minimal previous-version installation to support
pg_upgrade.