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.

2 files changed, 21 insertions, 6 deletions

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 075e4f54205..c44bbed3683 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 1.182.4.1 2005/08/25 19:44:52 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/access/heap/heapam.c,v 1.182.4.2 2010/07/29 16:15:47 rhaas Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -2304,8 +2304,16 @@ heap_xlog_newpage(bool redo, 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);
+	}
+
 	LockBuffer(buffer, BUFFER_LOCK_UNLOCK);
 	WriteBuffer(buffer);
 }
diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index b6d9d94e0d2..f82109bab35 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.142.4.12 2010/07/01 14:10:42 rhaas Exp $
+ *	  $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.142.4.13 2010/07/29 16:15:47 rhaas Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -5786,8 +5786,15 @@ copy_relation_data(Relation rel, SMgrRelation dst)
 
 			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();
 		}