From 1a078629acac290c972edeb6ae096e26b48ca032 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Thu, 29 Jul 2010 16:14:36 +0000
Subject: [PATCH] Fix possible page corruption by ALTER TABLE .. SET
 TABLESPACE.

If a zeroed page is present in the heap, ALTER TABLE .. SET TABLESPACE will
set the LSN and TLI while copying it, which is wrong, and heap_xlog_newpage()
will do the same thing during replay, so the corruption propagates to any
standby.  Note, however, that the bug can't be demonstrated unless archiving
is enabled, since in that case we skip WAL logging altogether, and the LSN/TLI
are not set.

Back-patch to 8.0; prior releases do not have tablespaces.

Analysis and patch by Jeff Davis.  Adjustments for back-branches and minor
wordsmithing by me.
---
 src/backend/access/heap/heapam.c | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index e17b6362c3..5eebfbc28f 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.292 2010/07/06 19:18:55 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.293 2010/07/29 16:14:36 rhaas Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -4079,8 +4079,15 @@ log_newpage(RelFileNode *rnode, ForkNumber forkNum, BlockNumber blkno,
 
 	recptr = XLogInsert(RM_HEAP_ID, XLOG_HEAP_NEWPAGE, rdata);
 
-	PageSetLSN(page, recptr);
-	PageSetTLI(page, ThisTimeLineID);
+	/*
+	 * The page may be uninitialized. If so, we can't set the LSN
+	 * and TLI because that would corrupt the page.
+	 */
+	if (!PageIsNew(page))
+	{
+		PageSetLSN(page, recptr);
+		PageSetTLI(page, ThisTimeLineID);
+	}
 
 	END_CRIT_SECTION();
 
@@ -4266,8 +4273,16 @@ heap_xlog_newpage(XLogRecPtr lsn, XLogRecord *record)
 	Assert(record->xl_len == SizeOfHeapNewpage + BLCKSZ);
 	memcpy(page, (char *) xlrec + SizeOfHeapNewpage, BLCKSZ);
 
-	PageSetLSN(page, lsn);
-	PageSetTLI(page, ThisTimeLineID);
+	/*
+	 * The page may be uninitialized. If so, we can't set the LSN
+	 * and TLI because that would corrupt the page.
+	 */
+	if (!PageIsNew(page))
+	{
+		PageSetLSN(page, lsn);
+		PageSetTLI(page, ThisTimeLineID);
+	}
+
 	MarkBufferDirty(buffer);
 	UnlockReleaseBuffer(buffer);
 }
-- 
2.40.0