v3-0001-cleanup-decoding-context-and-slots-in-error-cases.patch

From 25940eed0e79a0d7d6ea6dd18fa28109454e6fa6 Mon Sep 17 00:00:00 2001
From: Hou Zhijie <houzj.fnst@cn.fujitsu.com>
Date: Thu, 17 Aug 2023 19:29:34 +0800
Subject: [PATCH v3] cleanup decoding context and slots in error cases

Some of the management functions for logical decoding didn't clean up the
decoding context and slots when an error occurs during decoding. This can
result in accessing unfreed resources and assert failure the next time we call
these functions. Fix it by cleaning up the decoding context and slots in error
cases.

---
 src/backend/replication/logical/logicalfuncs.c | 18 ++++++++----------
 src/backend/replication/slotfuncs.c            | 13 ++++++-------
 2 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/src/backend/replication/logical/logicalfuncs.c b/src/backend/replication/logical/logicalfuncs.c
index 55a24c02c9..129d47faed 100644
--- a/src/backend/replication/logical/logicalfuncs.c
+++ b/src/backend/replication/logical/logicalfuncs.c
@@ -109,7 +109,7 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
 	MemoryContext per_query_ctx;
 	MemoryContext oldcontext;
 	XLogRecPtr	end_of_wal;
-	LogicalDecodingContext *ctx;
+	LogicalDecodingContext *volatile ctx = NULL;
 	ResourceOwner old_resowner = CurrentResourceOwner;
 	ArrayType  *arr;
 	Size		ndim;
@@ -297,19 +297,17 @@ pg_logical_slot_get_changes_guts(FunctionCallInfo fcinfo, bool confirm, bool bin
 			 */
 			ReplicationSlotMarkDirty();
 		}
-
-		/* free context, call shutdown callback */
-		FreeDecodingContext(ctx);
-
-		ReplicationSlotRelease();
-		InvalidateSystemCaches();
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
+		/* Free the context and call shutdown callback if necessary */
+		if (ctx != NULL)
+			FreeDecodingContext(ctx);
+
+		ReplicationSlotRelease();
+
 		/* clear all timetravel entries */
 		InvalidateSystemCaches();
-
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 
diff --git a/src/backend/replication/slotfuncs.c b/src/backend/replication/slotfuncs.c
index 6035cf4816..cc83a1e6f2 100644
--- a/src/backend/replication/slotfuncs.c
+++ b/src/backend/replication/slotfuncs.c
@@ -470,7 +470,7 @@ pg_physical_replication_slot_advance(XLogRecPtr moveto)
 static XLogRecPtr
 pg_logical_replication_slot_advance(XLogRecPtr moveto)
 {
-	LogicalDecodingContext *ctx;
+	LogicalDecodingContext *volatile ctx = NULL;
 	ResourceOwner old_resowner = CurrentResourceOwner;
 	XLogRecPtr	retlsn;
 
@@ -559,17 +559,16 @@ pg_logical_replication_slot_advance(XLogRecPtr moveto)
 
 		retlsn = MyReplicationSlot->data.confirmed_flush;
 
-		/* free context, call shutdown callback */
-		FreeDecodingContext(ctx);
-
 		InvalidateSystemCaches();
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
+		/* Free the context and call shutdown callback if necessary */
+		if (ctx != NULL)
+			FreeDecodingContext(ctx);
+
 		/* clear all timetravel entries */
 		InvalidateSystemCaches();
-
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 
-- 
2.30.0.windows.2