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Tom Lane 98fc31d649 Avoid race condition between "GRANT role" and "DROP ROLE".
Concurrently dropping either the granted role or the grantee
does not stop GRANT from completing, instead resulting in a
dangling role reference in pg_auth_members.  That's relatively
harmless in the short run, but inconsistent catalog entries
are not a good thing.

This patch solves the problem by adding the granted and grantee
roles as explicit shared dependencies of the pg_auth_members entry.
That's a bit indirect, but it works because the pg_shdepend code
applies the necessary locking and rechecking.

Commit 6566133c5 previously established similar handling for
the grantor column of pg_auth_members; it's not clear why it
didn't cover the other two role OID columns.

A side-effect of this approach is that DROP OWNED BY will now drop
pg_auth_members entries that mention the target role as either the
granted or grantee role.  That's clearly appropriate for the
grantee, since we'll drop its other privileges too.  It doesn't
seem too far out of line for the granted role, since we're
presumably about to drop it and besides we're removing all reasons
why it'd matter to be a member of it.  (One could argue that this
makes DropRole's code to auto-drop pg_auth_members entries
unnecessary, but I chose to leave it in place since perhaps some
people's workflows expect that to work without a DROP OWNED BY.)

Note to patch readers: CreateRole's first CommandCounterIncrement
call is now unconditional, because this change creates another
case in which it's needed, and it seemed to be more trouble than
it's worth to preserve that micro-optimization.

Arguably this is a bug fix, but the fact that it changes the
expected contents of pg_shdepend seems like not a great thing
to do in the stable branches, and perhaps we don't want the
change in DROP OWNED BY semantics there either.  On the other
hand, I opted not to force a catversion bump in HEAD, because
the presence or absence of these entries doesn't matter for
most purposes.

Reported-by: Virender Singla <virender.cse@gmail.com>
Reviewed-by: Laurenz Albe <laurenz.albe@cybertec.at>
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ=w87R2L0K8347iE-juQL2EA@mail.gmail.com
2025-02-21 17:07:01 -05:00
.github Add CODE_OF_CONDUCT.md, CONTRIBUTING.md, and SECURITY.md. 2024-07-02 13:03:58 -05:00
config Add support for OAUTHBEARER SASL mechanism 2025-02-20 16:25:17 +01:00
contrib Fix an issue with index scan using pg_trgm due to char signedness on different architectures. 2025-02-21 10:27:39 -08:00
doc Avoid race condition between "GRANT role" and "DROP ROLE". 2025-02-21 17:07:01 -05:00
src Avoid race condition between "GRANT role" and "DROP ROLE". 2025-02-21 17:07:01 -05:00
.cirrus.star Remove duplicate words in docs and code comments. 2023-10-09 09:18:47 +05:30
.cirrus.tasks.yml cirrus: Temporarily fix libcurl link error 2025-02-20 16:25:47 +01:00
.cirrus.yml ci: Test NetBSD and OpenBSD 2025-02-12 09:40:07 -05:00
.dir-locals.el Make Emacs perl-mode indent more like perltidy. 2019-01-13 11:32:31 -08:00
.editorconfig Add script to keep .editorconfig in sync with .gitattributes 2025-02-01 10:09:45 +01:00
.git-blame-ignore-revs Add commit 76aa615943 to .git-blame-ignore-revs 2025-02-01 16:48:18 +09:00
.gitattributes Add script to keep .editorconfig in sync with .gitattributes 2025-02-01 10:09:45 +01:00
.gitignore Update top-level .gitignore. 2022-12-04 15:23:00 -05:00
.mailmap Add a Git .mailmap file 2024-11-05 13:56:02 +01:00
aclocal.m4 autoconf: Move export_dynamic determination to configure 2022-12-06 18:55:28 -08:00
configure Add support for OAUTHBEARER SASL mechanism 2025-02-20 16:25:17 +01:00
configure.ac Add support for OAUTHBEARER SASL mechanism 2025-02-20 16:25:17 +01:00
COPYRIGHT Update copyright for 2025 2025-01-01 11:21:55 -05:00
GNUmakefile.in Allow selecting the git revision to be packaged by "make dist". 2024-05-03 11:08:50 -04:00
HISTORY Canonicalize some URLs 2020-02-10 20:47:50 +01:00
Makefile Remove AIX support 2024-02-28 15:17:23 +04:00
meson_options.txt Add support for OAUTHBEARER SASL mechanism 2025-02-20 16:25:17 +01:00
meson.build Make test portlock logic work with meson 2025-02-21 11:25:05 -05:00
README.md Revise the style of a paragraph in README.md. 2024-03-21 10:16:41 -05:00

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.

Copyright and license information can be found in the file COPYRIGHT.

General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.

The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.