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Tom Lane f20b840813 Prevent buffer overrun in unicode_normalize().
Some UTF8 characters decompose to more than a dozen codepoints.
It is possible for an input string that fits into well under
1GB to produce more than 4G decomposed codepoints, causing
unicode_normalize()'s decomp_size variable to wrap around to a
small positive value.  This results in a small output buffer
allocation and subsequent buffer overrun.

To fix, test after each addition to see if we've overrun MaxAllocSize,
and break out of the loop early if so.  In frontend code we want to
just return NULL for this failure (treating it like OOM).  In the
backend, we can rely on the following palloc() call to throw error.

I also tightened things up in the calling functions in varlena.c,
using size_t rather than int and allocating the input workspace
with palloc_array().  These changes are probably unnecessary
given the knowledge that the original input and the normalized
output_chars array must fit into 1GB, but it's a lot easier to
believe the code is safe with these changes.

Reported-by: Xint Code
Reported-by: Bruce Dang <bruce@calif.io>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Co-authored-by: Heikki Linnakangas <hlinnaka@iki.fi>
Backpatch-through: 14
Security: CVE-2026-6473
2026-05-11 05:13:49 -07:00
config Allow PG_PRINTF_ATTRIBUTE to be different in C and C++ code. 2026-02-25 11:57:26 -05:00
contrib ltree: Fix overflows with lquery parsing 2026-05-11 05:13:49 -07:00
doc Release notes for 18.4, 17.10, 16.14, 15.18, 14.23. 2026-05-10 12:07:32 -04:00
src Prevent buffer overrun in unicode_normalize(). 2026-05-11 05:13:49 -07:00
.abi-compliance-history Placate ABI checker. 2026-02-07 11:50:35 +13:00
.cirrus.star ci: Simplify ci-os-only handling 2025-08-14 12:03:27 -04:00
.cirrus.tasks.yml Fix typo 2026-01-07 15:49:00 +01:00
.cirrus.yml ci: Per-repo configuration for manually trigger tasks 2025-08-14 11:33:50 -04:00
.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 previous commit to .git-blame-ignore-revs. 2025-10-21 10:02:19 -05:00
.gitattributes Fix git whitespace warning 2025-08-15 10:31:52 +02:00
.gitignore Update top-level .gitignore. 2022-12-04 15:23:00 -05:00
aclocal.m4 autoconf: Move export_dynamic determination to configure 2022-12-06 18:55:28 -08:00
configure Allow PG_PRINTF_ATTRIBUTE to be different in C and C++ code. 2026-02-25 11:57:26 -05:00
configure.ac Allow PG_PRINTF_ATTRIBUTE to be different in C and C++ code. 2026-02-25 11:57:26 -05:00
COPYRIGHT Update copyright for 2026 2026-01-01 13:24:10 -05:00
GNUmakefile.in Integrate pg_bsd_indent into our build/test infrastructure. 2023-02-12 12:22:21 -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
meson.build Allow PG_PRINTF_ATTRIBUTE to be different in C and C++ code. 2026-02-25 11:57:26 -05:00
meson_options.txt meson: Attach colon to keyword argument 2023-06-29 12:53:41 +02:00
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

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/.