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[PATCH 2/6] Refactor index_concurrently_create_copy() for use with REPACK (CONCURRENTLY).
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* [PATCH 2/6] Refactor index_concurrently_create_copy() for use with REPACK (CONCURRENTLY).
@ 2026-01-12 16:30  Antonin Houska <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Antonin Houska @ 2026-01-12 16:30 UTC (permalink / raw)

This patch moves the code to index_create_copy() and adds a "concurrently"
parameter so it can be used by REPACK (CONCURRENTLY).

With the CONCURRENTLY option, REPACK cannot simply swap the heap file and
rebuild its indexes. Instead, it needs to build a separate set of indexes
(including system catalog entries) *before* the actual swap, to reduce the
time AccessExclusiveLock needs to be held for.
---
 src/backend/catalog/index.c      | 54 +++++++++++++++++++++++---------
 src/backend/commands/indexcmds.c |  6 ++--
 src/backend/nodes/makefuncs.c    |  9 +++---
 src/include/catalog/index.h      |  3 ++
 src/include/nodes/makefuncs.h    |  4 ++-
 5 files changed, 54 insertions(+), 22 deletions(-)

diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 5ee6389d39c..f8e6c3d804e 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -1288,15 +1288,32 @@ index_create(Relation heapRelation,
 /*
  * index_concurrently_create_copy
  *
- * Create concurrently an index based on the definition of the one provided by
- * caller.  The index is inserted into catalogs and needs to be built later
- * on.  This is called during concurrent reindex processing.
- *
- * "tablespaceOid" is the tablespace to use for this index.
+ * Variant of index_create_copy(), called during concurrent reindex
+ * processing.
  */
 Oid
 index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 							   Oid tablespaceOid, const char *newName)
+{
+	return index_create_copy(heapRelation, oldIndexId, tablespaceOid, newName,
+							 true);
+}
+
+/*
+ * index_create_copy
+ *
+ * Create an index based on the definition of the one provided by caller.  The
+ * index is inserted into catalogs. If 'concurrently' is TRUE, it needs to be
+ * built later on, otherwise it's built immediately.
+ *
+ * "tablespaceOid" is the tablespace to use for this index.
+ *
+ * The actual implementation of index_concurrently_create_copy(), reusable for
+ * other purposes.
+ */
+Oid
+index_create_copy(Relation heapRelation, Oid oldIndexId, Oid tablespaceOid,
+				  const char *newName, bool concurrently)
 {
 	Relation	indexRelation;
 	IndexInfo  *oldInfo,
@@ -1315,6 +1332,7 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 	List	   *indexColNames = NIL;
 	List	   *indexExprs = NIL;
 	List	   *indexPreds = NIL;
+	int			flags = 0;
 
 	indexRelation = index_open(oldIndexId, RowExclusiveLock);
 
@@ -1325,7 +1343,7 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 	 * Concurrent build of an index with exclusion constraints is not
 	 * supported.
 	 */
-	if (oldInfo->ii_ExclusionOps != NULL)
+	if (oldInfo->ii_ExclusionOps != NULL && concurrently)
 		ereport(ERROR,
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("concurrent index creation for exclusion constraints is not supported")));
@@ -1381,9 +1399,7 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 	}
 
 	/*
-	 * Build the index information for the new index.  Note that rebuild of
-	 * indexes with exclusion constraints is not supported, hence there is no
-	 * need to fill all the ii_Exclusion* fields.
+	 * Build the index information for the new index.
 	 */
 	newInfo = makeIndexInfo(oldInfo->ii_NumIndexAttrs,
 							oldInfo->ii_NumIndexKeyAttrs,
@@ -1392,10 +1408,13 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 							indexPreds,
 							oldInfo->ii_Unique,
 							oldInfo->ii_NullsNotDistinct,
-							false,	/* not ready for inserts */
-							true,
+							!concurrently,	/* isready */
+							concurrently,	/* concurrent */
 							indexRelation->rd_indam->amsummarizing,
-							oldInfo->ii_WithoutOverlaps);
+							oldInfo->ii_WithoutOverlaps,
+							oldInfo->ii_ExclusionOps,
+							oldInfo->ii_ExclusionProcs,
+							oldInfo->ii_ExclusionStrats);
 
 	/*
 	 * Extract the list of column names and the column numbers for the new
@@ -1433,6 +1452,9 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 		stattargets[i].isnull = isnull;
 	}
 
+	if (concurrently)
+		flags = INDEX_CREATE_SKIP_BUILD | INDEX_CREATE_CONCURRENT;
+
 	/*
 	 * Now create the new index.
 	 *
@@ -1456,7 +1478,7 @@ index_concurrently_create_copy(Relation heapRelation, Oid oldIndexId,
 							  indcoloptions->values,
 							  stattargets,
 							  reloptionsDatum,
-							  INDEX_CREATE_SKIP_BUILD | INDEX_CREATE_CONCURRENT,
+							  flags,
 							  0,
 							  true, /* allow table to be a system catalog? */
 							  false,	/* is_internal? */
@@ -2450,7 +2472,8 @@ BuildIndexInfo(Relation index)
 					   indexStruct->indisready,
 					   false,
 					   index->rd_indam->amsummarizing,
-					   indexStruct->indisexclusion && indexStruct->indisunique);
+					   indexStruct->indisexclusion && indexStruct->indisunique,
+					   NULL, NULL, NULL);
 
 	/* fill in attribute numbers */
 	for (i = 0; i < numAtts; i++)
@@ -2510,7 +2533,8 @@ BuildDummyIndexInfo(Relation index)
 					   indexStruct->indisready,
 					   false,
 					   index->rd_indam->amsummarizing,
-					   indexStruct->indisexclusion && indexStruct->indisunique);
+					   indexStruct->indisexclusion && indexStruct->indisunique,
+					   NULL, NULL, NULL);
 
 	/* fill in attribute numbers */
 	for (i = 0; i < numAtts; i++)
diff --git a/src/backend/commands/indexcmds.c b/src/backend/commands/indexcmds.c
index 635679cc1f2..34209bd1393 100644
--- a/src/backend/commands/indexcmds.c
+++ b/src/backend/commands/indexcmds.c
@@ -243,7 +243,8 @@ CheckIndexCompatible(Oid oldId,
 	 */
 	indexInfo = makeIndexInfo(numberOfAttributes, numberOfAttributes,
 							  accessMethodId, NIL, NIL, false, false,
-							  false, false, amsummarizing, isWithoutOverlaps);
+							  false, false, amsummarizing, isWithoutOverlaps,
+							  NULL, NULL, NULL);
 	typeIds = palloc_array(Oid, numberOfAttributes);
 	collationIds = palloc_array(Oid, numberOfAttributes);
 	opclassIds = palloc_array(Oid, numberOfAttributes);
@@ -930,7 +931,8 @@ DefineIndex(ParseState *pstate,
 							  !concurrent,
 							  concurrent,
 							  amissummarizing,
-							  stmt->iswithoutoverlaps);
+							  stmt->iswithoutoverlaps,
+							  NULL, NULL, NULL);
 
 	typeIds = palloc_array(Oid, numberOfAttributes);
 	collationIds = palloc_array(Oid, numberOfAttributes);
diff --git a/src/backend/nodes/makefuncs.c b/src/backend/nodes/makefuncs.c
index 2caec621d73..ca7e21e8349 100644
--- a/src/backend/nodes/makefuncs.c
+++ b/src/backend/nodes/makefuncs.c
@@ -834,7 +834,8 @@ IndexInfo *
 makeIndexInfo(int numattrs, int numkeyattrs, Oid amoid, List *expressions,
 			  List *predicates, bool unique, bool nulls_not_distinct,
 			  bool isready, bool concurrent, bool summarizing,
-			  bool withoutoverlaps)
+			  bool withoutoverlaps, Oid *exclusion_ops, Oid *exclusion_procs,
+			  uint16 *exclusion_strats)
 {
 	IndexInfo  *n = makeNode(IndexInfo);
 
@@ -863,9 +864,9 @@ makeIndexInfo(int numattrs, int numkeyattrs, Oid amoid, List *expressions,
 	n->ii_PredicateState = NULL;
 
 	/* exclusion constraints */
-	n->ii_ExclusionOps = NULL;
-	n->ii_ExclusionProcs = NULL;
-	n->ii_ExclusionStrats = NULL;
+	n->ii_ExclusionOps = exclusion_ops;
+	n->ii_ExclusionProcs = exclusion_procs;
+	n->ii_ExclusionStrats = exclusion_strats;
 
 	/* speculative inserts */
 	n->ii_UniqueOps = NULL;
diff --git a/src/include/catalog/index.h b/src/include/catalog/index.h
index b259c4141ed..3426087b445 100644
--- a/src/include/catalog/index.h
+++ b/src/include/catalog/index.h
@@ -99,6 +99,9 @@ extern Oid	index_concurrently_create_copy(Relation heapRelation,
 										   Oid oldIndexId,
 										   Oid tablespaceOid,
 										   const char *newName);
+extern Oid	index_create_copy(Relation heapRelation, Oid oldIndexId,
+							  Oid tablespaceOid, const char *newName,
+							  bool concurrently);
 
 extern void index_concurrently_build(Oid heapRelationId,
 									 Oid indexRelationId);
diff --git a/src/include/nodes/makefuncs.h b/src/include/nodes/makefuncs.h
index 982ec25ae14..dcea148ae1a 100644
--- a/src/include/nodes/makefuncs.h
+++ b/src/include/nodes/makefuncs.h
@@ -99,7 +99,9 @@ extern IndexInfo *makeIndexInfo(int numattrs, int numkeyattrs, Oid amoid,
 								List *expressions, List *predicates,
 								bool unique, bool nulls_not_distinct,
 								bool isready, bool concurrent,
-								bool summarizing, bool withoutoverlaps);
+								bool summarizing, bool withoutoverlaps,
+								Oid *exclusion_ops, Oid *exclusion_procs,
+								uint16 *exclusion_strats);
 
 extern Node *makeStringConst(char *str, int location);
 extern DefElem *makeDefElem(char *name, Node *arg, int location);
-- 
2.47.3


--=-=-=
Content-Type: text/x-diff
Content-Disposition: attachment;
 filename=v30-0003-Move-conversion-of-a-historic-to-MVCC-snapshot-to-a-.patch



^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--






^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--






^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--






^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--






^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v3 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 21 +++++-
 .../expected/role-membership-drop-member.out  | 75 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 51 +++++++++++++
 4 files changed, 147 insertions(+), 1 deletion(-)
  14.9% src/backend/commands/
  48.1% src/test/isolation/expected/
  36.1% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..375fb527af2 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,24 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role \"%s\" does not exist",
+								get_rolespec_name(rolespec))));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..5b267ea32c2
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,75 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..989fe996249
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,51 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--Dvg/WemKV0I3T/Od--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v4 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

The AccessShareLock is held until end of transaction, so an open transaction
that performed GRANT, CREATE ROLE ... ROLE, or REASSIGN OWNED BY will block a
concurrent DROP ROLE on the same role until it commits.

Note that this introduces a potential deadlock between GRANT and DROP ROLE
when both target overlapping roles. The deadlock is detected and one session is
aborted with an error, which is preferable to the pre-patch behavior of silently
creating orphaned catalog entries.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by: Surya Poondla <[email protected]>
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 20 +++-
 .../expected/role-membership-drop-member.out  | 97 +++++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 63 ++++++++++++
 4 files changed, 180 insertions(+), 1 deletion(-)
  11.5% src/backend/commands/
  49.2% src/test/isolation/expected/
  38.6% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..ab3cfb0b13f 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,23 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+
+			/* Recheck that the role still exists after locking. */
+			if (!SearchSysCacheExists1(AUTHOID, ObjectIdGetDatum(roleid)))
+				ereport(ERROR,
+						(errcode(ERRCODE_UNDEFINED_OBJECT),
+						 errmsg("role with OID %u does not exist", roleid)));
+		}
+
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..7daf48395ca
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,97 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
+step s1_begin: BEGIN;
+step s1_set_role: SET ROLE regress_role_member_cu;
+step s1_grant_cu: GRANT regress_role_group_cu TO CURRENT_USER;
+step s2_drop_member_cu: DROP ROLE regress_role_member_cu; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member_cu: <... completed>
+step s1_reset: RESET ROLE;
+step s2_check_orphans: 
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+
+count
+-----
+    0
+(1 row)
+
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..054326ac535
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,63 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned pg_auth_members
+# entries, or from operating on a stale OID.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+	CREATE ROLE regress_role_group_cu;
+	CREATE ROLE regress_role_member_cu;
+	GRANT regress_role_group_cu TO regress_role_member_cu WITH ADMIN OPTION;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+	DROP ROLE IF EXISTS regress_role_member_cu;
+	DROP ROLE IF EXISTS regress_role_group_cu;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_set_role	{ SET ROLE regress_role_member_cu; }
+step s1_grant_cu	{ GRANT regress_role_group_cu TO CURRENT_USER; }
+step s1_commit		{ COMMIT; }
+step s1_reset		{ RESET ROLE; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+step s2_drop_member_cu	{ DROP ROLE regress_role_member_cu; }
+step s2_check_orphans	{
+	SELECT count(*)
+	FROM pg_auth_members m
+	LEFT JOIN pg_authid ra ON m.roleid  = ra.oid
+	LEFT JOIN pg_authid me ON m.member  = me.oid
+	LEFT JOIN pg_authid gr ON m.grantor = gr.oid
+	WHERE ra.oid IS NULL OR me.oid IS NULL OR gr.oid IS NULL;
+}
+
+# GRANT role TO member and concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit s2_check_orphans
+
+# ALTER GROUP ADD USER and concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit s2_check_orphans
+
+# CREATE ROLE ... ROLE member and concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit s2_check_orphans
+
+# DROP OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role and concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
+
+# GRANT role TO CURRENT_USER and concurrent DROP of the current user
+permutation s1_begin s1_set_role s1_grant_cu s2_drop_member_cu s1_commit s1_reset s2_check_orphans
-- 
2.34.1


--fotX2lJRknAHpfH+--






^ permalink  raw  reply  [nested|flat] 249+ messages in thread

* [PATCH v2 2/2] Protect role resolution in roleSpecsToIds() against concurrent DROP
@ 2026-07-06 08:28  Bertrand Drouvot <[email protected]>
  0 siblings, 0 replies; 249+ messages in thread

From: Bertrand Drouvot @ 2026-07-06 08:28 UTC (permalink / raw)

roleSpecsToIds() resolves role names to OIDs without acquiring any lock.
A concurrent DROP ROLE that commits between this resolution and the caller's use
of the OID leaves the caller operating on a stale OID, which can create orphaned
pg_auth_members entries.

Fix this by acquiring AccessShareLock on each resolved role within
roleSpecsToIds(), ensuring the role cannot be dropped while any caller is using
its OID.

Author: Bertrand Drouvot <[email protected]>
Reported-by: Virender Singla <[email protected]>
Reviewed-by:
Discussion: https://postgr.es/m/aki6fMNLUx6%2BBR8K%40bdtpg
Discussion: https://postgr.es/m/CAM6Zo8woa62ZFHtMKox6a4jb8qQ%3Dw87R2L0K8347iE-juQL2EA%40mail.gmail.com
---
 src/backend/commands/user.c                   | 13 +++++-
 .../expected/role-membership-drop-member.out  | 36 ++++++++++++++++
 src/test/isolation/isolation_schedule         |  1 +
 .../specs/role-membership-drop-member.spec    | 43 +++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
  13.8% src/backend/commands/
  42.9% src/test/isolation/expected/
  42.2% src/test/isolation/specs/

diff --git a/src/backend/commands/user.c b/src/backend/commands/user.c
index 5b869e91c17..05ec753f4f0 100644
--- a/src/backend/commands/user.c
+++ b/src/backend/commands/user.c
@@ -1778,6 +1778,8 @@ ReassignOwnedObjects(ReassignOwnedStmt *stmt)
  * roleSpecsToIds
  *
  * Given a list of RoleSpecs, generate a list of role OIDs in the same order.
+ * Each role is locked with AccessShareLock to prevent concurrent DROP ROLE
+ * from removing it between resolution and the caller's catalog update.
  *
  * ROLESPEC_PUBLIC is not allowed.
  */
@@ -1792,7 +1794,16 @@ roleSpecsToIds(List *memberNames)
 		RoleSpec   *rolespec = lfirst_node(RoleSpec, l);
 		Oid			roleid;
 
-		roleid = get_rolespec_oid(rolespec, false);
+		if (rolespec->roletype == ROLESPEC_CSTRING)
+			roleid = RoleNameGetOid(rolespec->rolename,
+									AccessShareLock, false,
+									NULL, NULL);
+		else
+		{
+			roleid = get_rolespec_oid(rolespec, false);
+			LockSharedObject(AuthIdRelationId, roleid, 0,
+							 AccessShareLock);
+		}
 		result = lappend_oid(result, roleid);
 	}
 	return result;
diff --git a/src/test/isolation/expected/role-membership-drop-member.out b/src/test/isolation/expected/role-membership-drop-member.out
new file mode 100644
index 00000000000..e6cae59d2c9
--- /dev/null
+++ b/src/test/isolation/expected/role-membership-drop-member.out
@@ -0,0 +1,36 @@
+Parsed test spec with 2 sessions
+
+starting permutation: s1_begin s1_grant s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_grant: GRANT regress_role_group TO regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_alter_add s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_alter_add: ALTER GROUP regress_role_group ADD USER regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_create_role s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_create_role: CREATE ROLE regress_role_new ROLE regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_drop_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_drop_owned: DROP OWNED BY regress_role_member;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
+
+starting permutation: s1_begin s1_reassign_owned s2_drop_member s1_commit
+step s1_begin: BEGIN;
+step s1_reassign_owned: REASSIGN OWNED BY regress_role_member TO regress_role_group;
+step s2_drop_member: DROP ROLE regress_role_member; <waiting ...>
+step s1_commit: COMMIT;
+step s2_drop_member: <... completed>
diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule
index b8ebe92553c..8fb8b52b77f 100644
--- a/src/test/isolation/isolation_schedule
+++ b/src/test/isolation/isolation_schedule
@@ -128,3 +128,4 @@ test: matview-write-skew
 test: lock-nowait
 test: for-portion-of
 test: ddl-dependency-locking
+test: role-membership-drop-member
diff --git a/src/test/isolation/specs/role-membership-drop-member.spec b/src/test/isolation/specs/role-membership-drop-member.spec
new file mode 100644
index 00000000000..e0140826e52
--- /dev/null
+++ b/src/test/isolation/specs/role-membership-drop-member.spec
@@ -0,0 +1,43 @@
+# Test that role membership commands properly lock the grantee/member
+# role to prevent concurrent DROP ROLE from creating orphaned # pg_auth_members
+# entries.
+
+setup
+{
+	CREATE ROLE regress_role_group;
+	CREATE ROLE regress_role_member;
+}
+
+teardown
+{
+	DROP ROLE IF EXISTS regress_role_group;
+	DROP ROLE IF EXISTS regress_role_member;
+	DROP ROLE IF EXISTS regress_role_new;
+}
+
+session s1
+step s1_begin		{ BEGIN; }
+step s1_grant		{ GRANT regress_role_group TO regress_role_member; }
+step s1_alter_add	{ ALTER GROUP regress_role_group ADD USER regress_role_member; }
+step s1_create_role	{ CREATE ROLE regress_role_new ROLE regress_role_member; }
+step s1_drop_owned	{ DROP OWNED BY regress_role_member; }
+step s1_reassign_owned	{ REASSIGN OWNED BY regress_role_member TO regress_role_group; }
+step s1_commit		{ COMMIT; }
+
+session s2
+step s2_drop_member	{ DROP ROLE regress_role_member; }
+
+# GRANT role TO member - concurrent DROP of the member
+permutation s1_begin s1_grant s2_drop_member s1_commit
+
+# ALTER ROLE ADD USER - concurrent DROP of the member
+permutation s1_begin s1_alter_add s2_drop_member s1_commit
+
+# CREATE ROLE ... ROLE member - concurrent DROP of the member
+permutation s1_begin s1_create_role s2_drop_member s1_commit
+
+# DROP OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_drop_owned s2_drop_member s1_commit
+
+# REASSIGN OWNED BY role - concurrent DROP of the role
+permutation s1_begin s1_reassign_owned s2_drop_member s1_commit
-- 
2.34.1


--cOHldBwZEf1OqVbN--





^ permalink  raw  reply  [nested|flat] 249+ messages in thread