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Tom Lane f42ea8350d Fix use-after-free issue in regexp engine.
Commit cebc1d34e taught parseqatom() to optimize cases where a branch
contains only one, "messy", atom by getting rid of excess subRE nodes.
The way we really should do that is to keep the subRE built for the
"messy" child atom; but to avoid changing parseqatom's nominal API,
I made it delete that node after copying its fields to the outer subRE
made by parsebranch().  It seems that that actually worked at the time;
but it became dangerous after ea1268f63, because that later commit
allowed the lower invocation of parse() to return a subRE that was also
pointed to by some v->subs[] entry.  This meant we could wind up with a
dangling pointer in v->subs[], allowing a later backref to misbehave,
but only if that subRE struct had been reused in between.  So the damage
seems confined to cases like '((...))...(...\2'.

To fix, do what I should have done before and modify parseqatom's API
to make it possible for it to remove the caller's subRE instead of the
callee's.  That's safer because we know that subRE isn't complete yet,
so noplace else will have a pointer to it.

Per report from Mark Dilger.  Back-patch to v14 where the problematic
patches came in.

Discussion: https://postgr.es/m/0203588E-E609-43AF-9F4F-902854231EE7@enterprisedb.com
2021-08-07 22:27:13 -04:00
config Remove configure-time thread safety checking (thread_test.c). 2021-07-24 12:16:40 -04:00
contrib postgres_fdw: Fix issues with generated columns in foreign tables. 2021-08-05 20:00:01 +09:00
doc Fix wording 2021-08-06 20:56:18 +02:00
src Fix use-after-free issue in regexp engine. 2021-08-07 22:27:13 -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 list of ignorable pgindent commits for git-blame. 2021-06-22 09:06:32 -07:00
.gitattributes gitattributes: Add new entry to silence whitespace error 2021-06-05 07:57:31 +02:00
.gitignore Support for optimizing and emitting code in LLVM JIT provider. 2018-03-22 11:05:22 -07:00
aclocal.m4 Remove configure-time probe for DocBook DTD. 2020-11-30 15:24:13 -05:00
configure Remove configure-time thread safety checking (thread_test.c). 2021-07-24 12:16:40 -04:00
configure.ac Remove configure-time thread safety checking (thread_test.c). 2021-07-24 12:16:40 -04:00
COPYRIGHT Update copyright for 2021 2021-01-02 13:06:25 -05:00
GNUmakefile.in add missing tag from commit b8c4261e5e 2021-07-01 15:47:47 -04:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
Makefile Don't unset MAKEFLAGS in non-GNU Makefile. 2019-06-25 09:36:21 +12:00
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/.