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David Rowley a858327221 Fix 32-bit build dangling pointer issue in WindowAgg 
9d9c02ccd added window "run conditions", which allows the evaluation of
monotonic window functions to be skipped when the run condition is no
longer true.  Prior to this commit, once the run condition was no longer
true and we stopped evaluating the window functions, we simply just left
the ecxt_aggvalues[] and ecxt_aggnulls[] arrays alone to store whatever
value was stored there the last time the window function was evaluated.
Leaving a stale value in there isn't really a problem on 64-bit builds as
all of the window functions which we recognize as monotonic all return
int8, which is passed by value on 64-bit builds.  However, on 32-bit
builds, this was a problem as the value stored in the ecxt_values[]
element would be a by-ref value and it would be pointing to some memory
which would get reset once the tuple context is destroyed.  Since the
WindowAgg node will output these values in the resulting tupleslot, this
could be problematic for the top-level WindowAgg node which must look at
these values to filter out the rows that don't meet its filter condition.

Here we fix this by just zeroing the ecxt_aggvalues[] and setting the
ecxt_aggnulls[] array to true when the run condition first becomes false.
This results in the WindowAgg's output having NULLs for the WindowFunc's
columns rather than the stale or pointer pointing to possibly freed
memory.  These tuples with the NULLs can only make it as far as the
top-level WindowAgg node before they're filtered out.  To ensure that
these tuples *are* always filtered out, we now insist that OpExprs making
up the run condition are strict OpExprs.  Currently, all the window
functions which the planner recognizes as monotonic return INT8 and the
operator which is used for the run condition must be a member of a btree
opclass.  In reality, these restrictions exclude nothing that's built-in
to Postgres and are unlikely to exclude anyone's custom operators due to
the requirement that the operator is part of a btree opclass.  It would be
unusual if those were not strict.

Reported-by: Sergey Shinderuk, using valgrind
Reviewed-by: Richard Guo, Sergey Shinderuk
Discussion: https://postgr.es/m/29184c50-429a-ebd7-f1fb-0589c6723a35@postgrespro.ru
Backpatch-through: 15, where 9d9c02ccd was added
 		2022-12-07 00:09:36 +13:00
config autoconf: Unify CFLAGS_SSE42 and CFLAGS_ARMV8_CRC32C 2022-12-01 18:46:55 -08:00
contrib Stop accessing checkAsUser via RTE in some cases 2022-11-30 12:07:03 +01:00
doc pg_dump: Remove "blob" terminology 2022-12-05 08:52:55 +01:00
src Fix 32-bit build dangling pointer issue in WindowAgg 2022-12-07 00:09:36 +13:00
.cirrus.yml ci: Use -fsanitize=undefined,alignment,address in linux tasks 2022-11-21 15:13:09 -08:00
.dir-locals.el Make Emacs perl-mode indent more like perltidy. 2019-01-13 11:32:31 -08:00
.editorconfig Add .editorconfig 2019-12-18 09:13:13 +01:00
.git-blame-ignore-revs Add b2e6e7682 to .git-blame-ignore-revs 2022-09-08 14:06:59 +07:00
.gitattributes Remove trailing whitespace from *.sgml files. 2022-04-20 11:04:49 -04:00
.gitignore Update top-level .gitignore. 2022-12-04 15:23:00 -05:00
COPYRIGHT Update copyright for 2022 2022-01-07 19:04:57 -05:00
GNUmakefile.in Remove temporary portlock directory during make [dist]clean. 2022-11-26 10:30:31 -05:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
Makefile Dynamically find correct installation docs in Makefile. 2022-01-19 14:48:25 +01:00
README Canonicalize some URLs 2020-02-10 20:47:50 +01:00
README.git Canonicalize some URLs 2020-02-10 20:47:50 +01:00
aclocal.m4 Probe $PROVE not $PERL while checking for modules needed by TAP tests. 2021-11-22 12:54:52 -05:00
configure autoconf: Don't AC_SUBST() LD in configure 2022-12-01 19:03:26 -08:00
configure.ac autoconf: Don't AC_SUBST() LD in configure 2022-12-01 19:03:26 -08:00
meson.build meson: Fix binary mismatch for MSVC plperl vs gcc built perl libs 2022-11-28 11:43:31 -08:00
meson_options.txt Make finding openssl program a configure or meson option 2022-10-20 21:05:42 +02:00

README 

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:

	https://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.  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
https://www.postgresql.org/download/.  For more information look at our
web site located at https://www.postgresql.org/.