Thread: Major Version Upgrade failure due to orphan roles entries in catalog

On Tue, 2025-02-11 at 15:32 +0530, Virender Singla wrote:
> We have identified an issue causing upgrade failures. The following steps detail how to reproduce the issue:
>
> Create an orphan role entry
>
> /* Postgres version:: PostgreSQL 16.6 */ 
> /* The same can be reproduced in version 17 as well */
>
> create role my_group;
> create role dropped_member;
> begin;
> grant my_group to dropped_member;
> OTHER SESSION: drop role dropped_member;
> BACK IN ORIGINAL SESSION:
> commit;
>
> Upgrade to Postgres v17
>
> And the upgrade fails with an error :
>
> GRANT "my_group" TO "" WITH INHERIT TRUE GRANTED BY "postgres";
> ERROR: zero-length delimited identifier at or near """"
>
> The issue seems to be coming from pg_dumpall for building grants during pg_upgrade.
>
> https://github.com/postgres/postgres/blob/master/src/bin/pg_dump/pg_dumpall.c#L992

I agree that that is a bug.

I guess the GRANT statement should put a FOR KEY SHARE lock on the pg_authid row
for "dropped_member", similar to what we do for foreign keys.

Yours,
Laurenz Albe

--

*E-Mail Disclaimer*
Der Inhalt dieser E-Mail ist ausschliesslich fuer den
bezeichneten Adressaten bestimmt. Wenn Sie nicht der vorgesehene Adressat
dieser E-Mail oder dessen Vertreter sein sollten, so beachten Sie bitte,
dass jede Form der Kenntnisnahme, Veroeffentlichung, Vervielfaeltigung oder
Weitergabe des Inhalts dieser E-Mail unzulaessig ist. Wir bitten Sie, sich
in diesem Fall mit dem Absender der E-Mail in Verbindung zu setzen.

*CONFIDENTIALITY NOTICE & DISCLAIMER
*This message and any attachment are
confidential and may be privileged or otherwise protected from disclosure
and solely for the use of the person(s) or entity to whom it is intended.
If you have received this message in error and are not the intended
recipient, please notify the sender immediately and delete this message and
any attachment from your system. If you are not the intended recipient, be
advised that any use of this message is prohibited and may be unlawful, and
you must not copy this message or attachment or disclose the contents to
any other person.

Laurenz Albe <laurenz.albe@cybertec.at> writes:
> On Tue, 2025-02-11 at 15:32 +0530, Virender Singla wrote:
>> /* Postgres version:: PostgreSQL 16.6 */
>> /* The same can be reproduced in version 17 as well */
>>
>> create role my_group;
>> create role dropped_member;
>> begin;
>> grant my_group to dropped_member;
>> OTHER SESSION: drop role dropped_member;
>> BACK IN ORIGINAL SESSION:
>> commit;

[ leaves a dangling pg_auth_members entry behind ]

> I guess the GRANT statement should put a FOR KEY SHARE lock on the pg_authid row
> for "dropped_member", similar to what we do for foreign keys.

There is a lock taken already, which is why the DROP ROLE blocks.
What there is not is a recheck that the role still exists once
we have its lock.

I poked into this, and in code terms it seems like the problem is
that AddRoleMems adds a pg_auth_members entry but makes it depend
on only one of the three roles listed in the entry.  That seems
wrong on its face.  The connection to this problem is that the
dependency-adding code would take care of the lock+recheck, if
it only knew that the pg_auth_members entry ought to be treated
as depending on dropped_member.

The code the attached patch is touching is from commit 6566133c5.
I'm not going to blame the bug on that commit, because before that
we had dependencies on *zero* of the three roles; at least it added
one on the grantor.  But I'm wondering whether Robert thought about
the other two roles and explicitly rejected making dependencies
for them, and if so why.

In addition to fixing the described race condition, this patch
means that DROP OWNED BY on either the granted role or the member
will drop the grant.  This seems consistent with the goals of
6566133c5 and with our general approach to dropping privileges
during DROP OWNED BY; but it didn't happen that way before.

I'm wondering a little bit if we could simplify/remove some of the
code in user.c by relying on processing of these dependency entries
to carry the load instead during DROP ROLE.  But it passes check-world
as-is, so maybe leaving well enough alone is best.

            regards, tom lane

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 0db174e6f1..0c84886e82 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -30,6 +30,7 @@
 #include "commands/defrem.h"
 #include "commands/seclabel.h"
 #include "commands/user.h"
+#include "lib/qunique.h"
 #include "libpq/crypt.h"
 #include "miscadmin.h"
 #include "storage/lmgr.h"
@@ -489,7 +490,7 @@ CreateRole(ParseState *pstate, CreateRoleStmt *stmt)
      * Advance command counter so we can see new record; else tests in
      * AddRoleMems may fail.
      */
-    if (addroleto || adminmembers || rolemembers)
+    if (addroleto || adminmembers || rolemembers || !superuser())
         CommandCounterIncrement();

     /* Default grant. */
@@ -1904,7 +1905,8 @@ AddRoleMems(Oid currentUserId, const char *rolename, Oid roleid,
         else
         {
             Oid            objectId;
-            Oid           *newmembers = palloc(sizeof(Oid));
+            Oid           *newmembers = (Oid *) palloc(3 * sizeof(Oid));
+            int            nnewmembers;

             /*
              * The values for these options can be taken directly from 'popt'.
@@ -1946,12 +1948,22 @@ AddRoleMems(Oid currentUserId, const char *rolename, Oid roleid,
                                     new_record, new_record_nulls);
             CatalogTupleInsert(pg_authmem_rel, tuple);

-            /* updateAclDependencies wants to pfree array inputs */
-            newmembers[0] = grantorId;
+            /*
+             * Record dependencies on the roleid, member, and grantor, as if a
+             * pg_auth_members entry were an object ACL.
+             * updateAclDependencies() requires an input array that is
+             * palloc'd (it will free it), sorted, and de-duped.
+             */
+            newmembers[0] = roleid;
+            newmembers[1] = memberid;
+            newmembers[2] = grantorId;
+            qsort(newmembers, 3, sizeof(Oid), oid_cmp);
+            nnewmembers = qunique(newmembers, 3, sizeof(Oid), oid_cmp);
+
             updateAclDependencies(AuthMemRelationId, objectId,
                                   0, InvalidOid,
                                   0, NULL,
-                                  1, newmembers);
+                                  nnewmembers, newmembers);
         }

         /* CCI after each change, in case there are duplicates in list */

On 2025-Feb-11, Virender Singla wrote:

> And the upgrade fails with an error :
> 
> 
> *GRANT "my_group" TO "" WITH INHERIT TRUE GRANTED BY "postgres";ERROR:
> zero-length delimited identifier at or near """"*
> 
> The issue seems to be coming from pg_dumpall for building grants during
> pg_upgrade.

Hmm, I think fixing the bug as Tom suggests downthread is probably a
good idea, but I think we should in addition change pg_dumpall to avoid
printing a GRANT line if there's no grantee.  Maybe turning one of these LEFT
JOINs into a regular inner join is a sufficient fix for that:

    /* Generate and execute query. */
    printfPQExpBuffer(buf, "SELECT ur.rolname AS role, "
                      "um.rolname AS member, "
                      "ug.oid AS grantorid, "
                      "ug.rolname AS grantor, "
                      "a.admin_option");
    if (dump_grant_options)
        appendPQExpBufferStr(buf, ", a.inherit_option, a.set_option");
    appendPQExpBuffer(buf, " FROM pg_auth_members a "
                      "LEFT JOIN %s ur on ur.oid = a.roleid "
                      "LEFT JOIN %s um on um.oid = a.member "
                      "LEFT JOIN %s ug on ug.oid = a.grantor "
                      "WHERE NOT (ur.rolname ~ '^pg_' AND um.rolname ~ '^pg_')"
                      "ORDER BY 1,2,4", role_catalog, role_catalog, role_catalog);

-- 
Álvaro Herrera        Breisgau, Deutschland  —  https://www.EnterpriseDB.com/
"I am amazed at [the pgsql-sql] mailing list for the wonderful support, and
lack of hesitasion in answering a lost soul's question, I just wished the rest
of the mailing list could be like this."                               (Fotis)
              https://postgr.es/m/200606261359.k5QDxE2p004593@auth-smtp.hol.gr

=?utf-8?Q?=C3=81lvaro?= Herrera <alvherre@alvh.no-ip.org> writes:
> Hmm, I think fixing the bug as Tom suggests downthread is probably a
> good idea, but I think we should in addition change pg_dumpall to avoid
> printing a GRANT line if there's no grantee.

On the one hand, my proposed patch can do nothing to fix existing
dangling entries in pg_auth_members, so hacking pg_dump seems like
a good workaround if the problem already exists.  On the other hand,
if we make pg_dump do that then we won't detect future problems of
the same ilk.

> Maybe turning one of these LEFT
> JOINs into a regular inner join is a sufficient fix for that:

Probably change all three, if we're to do this at all.

            regards, tom lane

=?utf-8?Q?=C3=81lvaro?= Herrera <alvherre@alvh.no-ip.org> writes:
> Hmm, I think fixing the bug as Tom suggests downthread is probably a
> good idea, but I think we should in addition change pg_dumpall to avoid
> printing a GRANT line if there's no grantee.  Maybe turning one of these LEFT
> JOINs into a regular inner join is a sufficient fix for that:

After looking at this I thought it was worth a little more code to warn
about the dangling role OID, instead of just silently ignoring it.
Here's a couple of more-polished patches.

I'm unsure whether to back-patch the 0001 patch, as it does imply
more pg_shdepend entries than we have today, so it's sort of a
backdoor catalog change.  But we're mostly interested in the
transient behavior of having a lock+recheck during entry insertion,
so maybe it's fine.  0002 should be back-patched in any case.

(BTW, I was distressed to learn from the code coverage report
that we have zero test coverage of the hardly-trivial logic in
dumpRoleMembership.  I didn't try to address that here.  I did
test this new logic by dint of manually deleting from pg_authid.)

            regards, tom lane

From b8f0dff492cfe689e8516b0353d004f483838640 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 20 Feb 2025 15:34:55 -0500
Subject: [PATCH v1 1/2] 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 it does result in garbage
output from pg_dumpall and therefore problems for pg_upgrade.

This patch deals with 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, and it doesn't seem too far out of line for
the granted role.  (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.)

Reported-by: Virender Singla <virender.cse@gmail.com>
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ=w87R2L0K8347iE-juQL2EA@mail.gmail.com
Backpatch-through: TBD
---
 doc/src/sgml/ref/drop_owned.sgml         |  2 +-
 src/backend/commands/user.c              | 22 +++++++++++++----
 src/test/regress/expected/privileges.out | 30 ++++++++++++++++++++++++
 src/test/regress/sql/privileges.sql      | 15 ++++++++++++
 4 files changed, 63 insertions(+), 6 deletions(-)

diff --git a/doc/src/sgml/ref/drop_owned.sgml b/doc/src/sgml/ref/drop_owned.sgml
index efda01a39e..46e1c229ec 100644
--- a/doc/src/sgml/ref/drop_owned.sgml
+++ b/doc/src/sgml/ref/drop_owned.sgml
@@ -33,7 +33,7 @@ DROP OWNED BY { <replaceable class="parameter">name</replaceable> | CURRENT_ROLE
    database that are owned by one of the specified roles. Any
    privileges granted to the given roles on objects in the current
    database or on shared objects (databases, tablespaces, configuration
-   parameters) will also be revoked.
+   parameters, or other roles) will also be revoked.
   </para>
  </refsect1>

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 0db174e6f1..0c84886e82 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -30,6 +30,7 @@
 #include "commands/defrem.h"
 #include "commands/seclabel.h"
 #include "commands/user.h"
+#include "lib/qunique.h"
 #include "libpq/crypt.h"
 #include "miscadmin.h"
 #include "storage/lmgr.h"
@@ -489,7 +490,7 @@ CreateRole(ParseState *pstate, CreateRoleStmt *stmt)
      * Advance command counter so we can see new record; else tests in
      * AddRoleMems may fail.
      */
-    if (addroleto || adminmembers || rolemembers)
+    if (addroleto || adminmembers || rolemembers || !superuser())
         CommandCounterIncrement();

     /* Default grant. */
@@ -1904,7 +1905,8 @@ AddRoleMems(Oid currentUserId, const char *rolename, Oid roleid,
         else
         {
             Oid            objectId;
-            Oid           *newmembers = palloc(sizeof(Oid));
+            Oid           *newmembers = (Oid *) palloc(3 * sizeof(Oid));
+            int            nnewmembers;

             /*
              * The values for these options can be taken directly from 'popt'.
@@ -1946,12 +1948,22 @@ AddRoleMems(Oid currentUserId, const char *rolename, Oid roleid,
                                     new_record, new_record_nulls);
             CatalogTupleInsert(pg_authmem_rel, tuple);

-            /* updateAclDependencies wants to pfree array inputs */
-            newmembers[0] = grantorId;
+            /*
+             * Record dependencies on the roleid, member, and grantor, as if a
+             * pg_auth_members entry were an object ACL.
+             * updateAclDependencies() requires an input array that is
+             * palloc'd (it will free it), sorted, and de-duped.
+             */
+            newmembers[0] = roleid;
+            newmembers[1] = memberid;
+            newmembers[2] = grantorId;
+            qsort(newmembers, 3, sizeof(Oid), oid_cmp);
+            nnewmembers = qunique(newmembers, 3, sizeof(Oid), oid_cmp);
+
             updateAclDependencies(AuthMemRelationId, objectId,
                                   0, InvalidOid,
                                   0, NULL,
-                                  1, newmembers);
+                                  nnewmembers, newmembers);
         }

         /* CCI after each change, in case there are duplicates in list */
diff --git a/src/test/regress/expected/privileges.out b/src/test/regress/expected/privileges.out
index 6b01313101..a76256405f 100644
--- a/src/test/regress/expected/privileges.out
+++ b/src/test/regress/expected/privileges.out
@@ -113,6 +113,36 @@ CREATE USER regress_priv_user2;
 CREATE USER regress_priv_user3;
 CREATE USER regress_priv_user4;
 CREATE USER regress_priv_user5;
+-- DROP OWNED should also act on granted and granted-to roles
+GRANT regress_priv_user1 TO regress_priv_user2;
+GRANT regress_priv_user2 TO regress_priv_user3;
+SELECT roleid::regrole, member::regrole FROM pg_auth_members
+  WHERE roleid IN ('regress_priv_user1'::regrole,'regress_priv_user2'::regrole)
+  ORDER BY roleid::regrole::text;
+       roleid       |       member
+--------------------+--------------------
+ regress_priv_user1 | regress_priv_user2
+ regress_priv_user2 | regress_priv_user3
+(2 rows)
+
+REASSIGN OWNED BY regress_priv_user2 TO regress_priv_user4;  -- no effect
+SELECT roleid::regrole, member::regrole FROM pg_auth_members
+  WHERE roleid IN ('regress_priv_user1'::regrole,'regress_priv_user2'::regrole)
+  ORDER BY roleid::regrole::text;
+       roleid       |       member
+--------------------+--------------------
+ regress_priv_user1 | regress_priv_user2
+ regress_priv_user2 | regress_priv_user3
+(2 rows)
+
+DROP OWNED BY regress_priv_user2;  -- removes both grants
+SELECT roleid::regrole, member::regrole FROM pg_auth_members
+  WHERE roleid IN ('regress_priv_user1'::regrole,'regress_priv_user2'::regrole)
+  ORDER BY roleid::regrole::text;
+ roleid | member
+--------+--------
+(0 rows)
+
 GRANT pg_read_all_data TO regress_priv_user6;
 GRANT pg_write_all_data TO regress_priv_user7;
 GRANT pg_read_all_settings TO regress_priv_user8 WITH ADMIN OPTION;
diff --git a/src/test/regress/sql/privileges.sql b/src/test/regress/sql/privileges.sql
index 60e7443bf5..d195aaf137 100644
--- a/src/test/regress/sql/privileges.sql
+++ b/src/test/regress/sql/privileges.sql
@@ -90,6 +90,21 @@ CREATE USER regress_priv_user3;
 CREATE USER regress_priv_user4;
 CREATE USER regress_priv_user5;

+-- DROP OWNED should also act on granted and granted-to roles
+GRANT regress_priv_user1 TO regress_priv_user2;
+GRANT regress_priv_user2 TO regress_priv_user3;
+SELECT roleid::regrole, member::regrole FROM pg_auth_members
+  WHERE roleid IN ('regress_priv_user1'::regrole,'regress_priv_user2'::regrole)
+  ORDER BY roleid::regrole::text;
+REASSIGN OWNED BY regress_priv_user2 TO regress_priv_user4;  -- no effect
+SELECT roleid::regrole, member::regrole FROM pg_auth_members
+  WHERE roleid IN ('regress_priv_user1'::regrole,'regress_priv_user2'::regrole)
+  ORDER BY roleid::regrole::text;
+DROP OWNED BY regress_priv_user2;  -- removes both grants
+SELECT roleid::regrole, member::regrole FROM pg_auth_members
+  WHERE roleid IN ('regress_priv_user1'::regrole,'regress_priv_user2'::regrole)
+  ORDER BY roleid::regrole::text;
+
 GRANT pg_read_all_data TO regress_priv_user6;
 GRANT pg_write_all_data TO regress_priv_user7;
 GRANT pg_read_all_settings TO regress_priv_user8 WITH ADMIN OPTION;
--
2.43.5

From 937b1ebb7c8eeb022385c51ec13ea206bd97d2a3 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Thu, 20 Feb 2025 17:07:34 -0500
Subject: [PATCH v1 2/2] Fix pg_dumpall to cope with dangling OIDs in
 pg_auth_members.

In view of the bug fixed by the previous patch, we need to allow
for the possibility of role OIDs in pg_auth_members that don't
exist in pg_authid.  As pg_dumpall stands, it will emit invalid
commands like 'GRANT foo TO ""', which causes pg_upgrade to fail.
Fix it to emit warnings and skip those GRANTs, instead.

There was some discussion of removing the problem by changing
dumpRoleMembership's query to use JOIN not LEFT JOIN, but that
would result in silently ignoring such entries.  It seems better
to produce a warning.

Reported-by: Virender Singla <virender.cse@gmail.com>
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ=w87R2L0K8347iE-juQL2EA@mail.gmail.com
Backpatch-through: TBD
---
 src/bin/pg_dump/pg_dumpall.c | 66 +++++++++++++++++++++++++++++++-----
 1 file changed, 57 insertions(+), 9 deletions(-)

diff --git a/src/bin/pg_dump/pg_dumpall.c b/src/bin/pg_dump/pg_dumpall.c
index b993b05cc2..b9b22c47be 100644
--- a/src/bin/pg_dump/pg_dumpall.c
+++ b/src/bin/pg_dump/pg_dumpall.c
@@ -986,6 +986,13 @@ dumpRoleMembership(PGconn *conn)
                 total;
     bool        dump_grantors;
     bool        dump_grant_options;
+    int            i_role;
+    int            i_member;
+    int            i_grantor;
+    int            i_roleid;
+    int            i_memberid;
+    int            i_grantorid;
+    int            i_admin_option;
     int            i_inherit_option;
     int            i_set_option;

@@ -995,6 +1002,10 @@ dumpRoleMembership(PGconn *conn)
      * they didn't have ADMIN OPTION on the role, or a user that no longer
      * existed. To avoid dump and restore failures, don't dump the grantor
      * when talking to an old server version.
+     *
+     * Also, in older versions the roleid and/or member could be role OIDs
+     * that no longer exist.  If we find such cases, print a warning and skip
+     * the entry.
      */
     dump_grantors = (PQserverVersion(conn) >= 160000);

@@ -1006,8 +1017,10 @@ dumpRoleMembership(PGconn *conn)
     /* Generate and execute query. */
     printfPQExpBuffer(buf, "SELECT ur.rolname AS role, "
                       "um.rolname AS member, "
-                      "ug.oid AS grantorid, "
                       "ug.rolname AS grantor, "
+                      "a.roleid AS roleid, "
+                      "a.member AS memberid, "
+                      "a.grantor AS grantorid, "
                       "a.admin_option");
     if (dump_grant_options)
         appendPQExpBufferStr(buf, ", a.inherit_option, a.set_option");
@@ -1016,8 +1029,15 @@ dumpRoleMembership(PGconn *conn)
                       "LEFT JOIN %s um on um.oid = a.member "
                       "LEFT JOIN %s ug on ug.oid = a.grantor "
                       "WHERE NOT (ur.rolname ~ '^pg_' AND um.rolname ~ '^pg_')"
-                      "ORDER BY 1,2,4", role_catalog, role_catalog, role_catalog);
+                      "ORDER BY 1,2,3", role_catalog, role_catalog, role_catalog);
     res = executeQuery(conn, buf->data);
+    i_role = PQfnumber(res, "role");
+    i_member = PQfnumber(res, "member");
+    i_grantor = PQfnumber(res, "grantor");
+    i_roleid = PQfnumber(res, "roleid");
+    i_memberid = PQfnumber(res, "memberid");
+    i_grantorid = PQfnumber(res, "grantorid");
+    i_admin_option = PQfnumber(res, "admin_option");
     i_inherit_option = PQfnumber(res, "inherit_option");
     i_set_option = PQfnumber(res, "set_option");

@@ -1041,24 +1061,32 @@ dumpRoleMembership(PGconn *conn)
     total = PQntuples(res);
     while (start < total)
     {
-        char       *role = PQgetvalue(res, start, 0);
+        char       *role = PQgetvalue(res, start, i_role);
         int            i;
         bool       *done;
         int            remaining;
         int            prev_remaining = 0;
         rolename_hash *ht;

+        /* If we hit a null roleid, we're done (nulls sort to the end). */
+        if (PQgetisnull(res, start, i_role))
+        {
+            /* translator: %s represents a numeric role OID */
+            pg_log_warning("found dangling pg_auth_members entry for role %s",
+                           PQgetvalue(res, start, i_roleid));
+            break;
+        }
+
         /* All memberships for a single role should be adjacent. */
         for (end = start; end < total; ++end)
         {
             char       *otherrole;

-            otherrole = PQgetvalue(res, end, 0);
+            otherrole = PQgetvalue(res, end, i_role);
             if (strcmp(role, otherrole) != 0)
                 break;
         }

-        role = PQgetvalue(res, start, 0);
         remaining = end - start;
         done = pg_malloc0(remaining * sizeof(bool));
         ht = rolename_create(remaining, NULL);
@@ -1098,10 +1126,30 @@ dumpRoleMembership(PGconn *conn)
                 if (done[i - start])
                     continue;

-                member = PQgetvalue(res, i, 1);
-                grantorid = PQgetvalue(res, i, 2);
-                grantor = PQgetvalue(res, i, 3);
-                admin_option = PQgetvalue(res, i, 4);
+                /* Complain about, then ignore, entries with dangling OIDs. */
+                if (PQgetisnull(res, i, i_member))
+                {
+                    /* translator: %s represents a numeric role OID */
+                    pg_log_warning("found dangling pg_auth_members entry for role %s",
+                                   PQgetvalue(res, i, i_memberid));
+                    done[i - start] = true;
+                    --remaining;
+                    continue;
+                }
+                if (PQgetisnull(res, i, i_grantor))
+                {
+                    /* translator: %s represents a numeric role OID */
+                    pg_log_warning("found dangling pg_auth_members entry for role %s",
+                                   PQgetvalue(res, i, i_grantorid));
+                    done[i - start] = true;
+                    --remaining;
+                    continue;
+                }
+
+                member = PQgetvalue(res, i, i_member);
+                grantor = PQgetvalue(res, i, i_grantor);
+                grantorid = PQgetvalue(res, i, i_grantorid);
+                admin_option = PQgetvalue(res, i, i_admin_option);
                 if (dump_grant_options)
                     set_option = PQgetvalue(res, i, i_set_option);

--
2.43.5

On Thu, 2025-02-20 at 17:19 -0500, Tom Lane wrote:
> After looking at this I thought it was worth a little more code to warn
> about the dangling role OID, instead of just silently ignoring it.
> Here's a couple of more-polished patches.
> 
> I'm unsure whether to back-patch the 0001 patch, as it does imply
> more pg_shdepend entries than we have today, so it's sort of a
> backdoor catalog change.  But we're mostly interested in the
> transient behavior of having a lock+recheck during entry insertion,
> so maybe it's fine.  0002 should be back-patched in any case.

I'd say that adding new catalog entries in a way that is compatible
shouldn't be a problem, but I still wouldn't backpatch the 0001 patch,
because it is not necessary.  The orphaned pg_auth_members entry didn't
cause any harm, and a few warnings more during an upgrade shouldn't be
a big problem.

I have one question about the first patch:

> diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
> index 0db174e6f1..0c84886e82 100644
> --- a/src/backend/commands/user.c
> +++ b/src/backend/commands/user.c
> @@ -489,7 +490,7 @@ CreateRole(ParseState *pstate, CreateRoleStmt *stmt)
>       * Advance command counter so we can see new record; else tests in
>       * AddRoleMems may fail.
>       */
> -    if (addroleto || adminmembers || rolemembers)
> +    if (addroleto || adminmembers || rolemembers || !superuser())
>          CommandCounterIncrement();
>  
>      /* Default grant. */

That change seems unrelated to the problem at hand, and I don't see it
mentioned in the commit message.  Is that an oversight you fixed on the
fly?

Apart from that, the patches look fine.

Yours,
Laurenz Albe

-- 

*E-Mail Disclaimer*
Der Inhalt dieser E-Mail ist ausschliesslich fuer den 
bezeichneten Adressaten bestimmt. Wenn Sie nicht der vorgesehene Adressat 
dieser E-Mail oder dessen Vertreter sein sollten, so beachten Sie bitte, 
dass jede Form der Kenntnisnahme, Veroeffentlichung, Vervielfaeltigung oder 
Weitergabe des Inhalts dieser E-Mail unzulaessig ist. Wir bitten Sie, sich 
in diesem Fall mit dem Absender der E-Mail in Verbindung zu setzen.

*CONFIDENTIALITY NOTICE & DISCLAIMER
*This message and any attachment are 
confidential and may be privileged or otherwise protected from disclosure 
and solely for the use of the person(s) or entity to whom it is intended. 
If you have received this message in error and are not the intended 
recipient, please notify the sender immediately and delete this message and 
any attachment from your system. If you are not the intended recipient, be 
advised that any use of this message is prohibited and may be unlawful, and 
you must not copy this message or attachment or disclose the contents to 
any other person.

Laurenz Albe <laurenz.albe@cybertec.at> writes:
> I have one question about the first patch:

>> -    if (addroleto || adminmembers || rolemembers)
>> +    if (addroleto || adminmembers || rolemembers || !superuser())
>>         CommandCounterIncrement();

> That change seems unrelated to the problem at hand, and I don't see it
> mentioned in the commit message.  Is that an oversight you fixed on the
> fly?

Well, kinda, because the patch doesn't work without it.  The
problematic case is where none of those 3 flags are set and also
!superuser, so that we decide we need the default grant implemented a
few lines further down.  That grant now has an explicit reference to
the new roleid, and if we haven't CommandCounterIncrement'ed, the
pg_shdepend code will error out because it doesn't see the catalog
entry for roleid.

            regards, tom lane

On Fri, 2025-02-21 at 09:41 -0500, Tom Lane wrote:
> Laurenz Albe <laurenz.albe@cybertec.at> writes:
> > I have one question about the first patch:
> 
> > > -    if (addroleto || adminmembers || rolemembers)
> > > +    if (addroleto || adminmembers || rolemembers || !superuser())
> > >         CommandCounterIncrement();
> 
> > That change seems unrelated to the problem at hand, and I don't see it
> > mentioned in the commit message.  Is that an oversight you fixed on the
> > fly?
> 
> Well, kinda, because the patch doesn't work without it.  The
> problematic case is where none of those 3 flags are set and also
> !superuser, so that we decide we need the default grant implemented a
> few lines further down.  That grant now has an explicit reference to
> the new roleid, and if we haven't CommandCounterIncrement'ed, the
> pg_shdepend code will error out because it doesn't see the catalog
> entry for roleid.

Thanks for the explanation.  That might be worth a comment.

Yours,
Laurenz Albe

-- 

*E-Mail Disclaimer*
Der Inhalt dieser E-Mail ist ausschliesslich fuer den 
bezeichneten Adressaten bestimmt. Wenn Sie nicht der vorgesehene Adressat 
dieser E-Mail oder dessen Vertreter sein sollten, so beachten Sie bitte, 
dass jede Form der Kenntnisnahme, Veroeffentlichung, Vervielfaeltigung oder 
Weitergabe des Inhalts dieser E-Mail unzulaessig ist. Wir bitten Sie, sich 
in diesem Fall mit dem Absender der E-Mail in Verbindung zu setzen.

*CONFIDENTIALITY NOTICE & DISCLAIMER
*This message and any attachment are 
confidential and may be privileged or otherwise protected from disclosure 
and solely for the use of the person(s) or entity to whom it is intended. 
If you have received this message in error and are not the intended 
recipient, please notify the sender immediately and delete this message and 
any attachment from your system. If you are not the intended recipient, be 
advised that any use of this message is prohibited and may be unlawful, and 
you must not copy this message or attachment or disclose the contents to 
any other person.

Laurenz Albe <laurenz.albe@cybertec.at> writes:
> Thanks for the explanation.  That might be worth a comment.

The adjacent comment already says

    /*
     * Advance command counter so we can see new record; else tests in
     * AddRoleMems may fail.
     */

so I didn't see anything to add there.  Maybe "We can skip this in
cases where we will not call AddRoleMems"?  Or maybe the better answer
is to conclude that the whole idea of not calling
CommandCounterIncrement unconditionally is too fragile and not worth
expending brain cells on, and just rip out the if-test.

            regards, tom lane

On Fri, 2025-02-21 at 11:31 -0500, Tom Lane wrote:
> Laurenz Albe <laurenz.albe@cybertec.at> writes:
> > Thanks for the explanation.  That might be worth a comment.
> 
> The adjacent comment already says
> 
>     /*
>      * Advance command counter so we can see new record; else tests in
>      * AddRoleMems may fail.
>      */
> 
> so I didn't see anything to add there.  Maybe "We can skip this in
> cases where we will not call AddRoleMems"?  Or maybe the better answer
> is to conclude that the whole idea of not calling
> CommandCounterIncrement unconditionally is too fragile and not worth
> expending brain cells on, and just rip out the if-test.

Both the extra sentence and the simplification feel like an improvement.
I am fine with either.

Yours,
Laurenz Albe

-- 

*E-Mail Disclaimer*
Der Inhalt dieser E-Mail ist ausschliesslich fuer den 
bezeichneten Adressaten bestimmt. Wenn Sie nicht der vorgesehene Adressat 
dieser E-Mail oder dessen Vertreter sein sollten, so beachten Sie bitte, 
dass jede Form der Kenntnisnahme, Veroeffentlichung, Vervielfaeltigung oder 
Weitergabe des Inhalts dieser E-Mail unzulaessig ist. Wir bitten Sie, sich 
in diesem Fall mit dem Absender der E-Mail in Verbindung zu setzen.

*CONFIDENTIALITY NOTICE & DISCLAIMER
*This message and any attachment are 
confidential and may be privileged or otherwise protected from disclosure 
and solely for the use of the person(s) or entity to whom it is intended. 
If you have received this message in error and are not the intended 
recipient, please notify the sender immediately and delete this message and 
any attachment from your system. If you are not the intended recipient, be 
advised that any use of this message is prohibited and may be unlawful, and 
you must not copy this message or attachment or disclose the contents to 
any other person.

Laurenz Albe <laurenz.albe@cybertec.at> writes:
> On Fri, 2025-02-21 at 11:31 -0500, Tom Lane wrote:
>> ... Or maybe the better answer
>> is to conclude that the whole idea of not calling
>> CommandCounterIncrement unconditionally is too fragile and not worth
>> expending brain cells on, and just rip out the if-test.

> Both the extra sentence and the simplification feel like an improvement.
> I am fine with either.

The more I think about it the more I like just getting rid of the
test.  It'll likely break with every future change to this logic,
until somebody finally gives up on it; so why not now?

I'll make it so.  Thanks for reviewing!

            regards, tom lane