postgres.git / summary / log / commit / refs

commit    7dc721889b31450cad338a189a97ff0ff46534d5
Author:   Heikki Linnakangas <heikki.linnakangas@iki.fi>
Date:     Tue Jun 30 10:37:16 2015 +0000

    Don't call PageGetSpecialPointer() on page until it's been initialized.
    
    After calling XLogInitBufferForRedo(), the page might be all-zeros if it was
    not in page cache already. btree_xlog_unlink_page initialized the page
    correctly, but it called PageGetSpecialPointer before initializing it, which
    would lead to a corrupt page at WAL replay, if the unlinked page is not in
    page cache.
    
    Backpatch to 9.4, the bug came with the rewrite of B-tree page deletion.


 src/backend/access/nbtree/nbtxlog.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/backend/access/nbtree/nbtxlog.c b/src/backend/access/nbtree/nbtxlog.c
index 5f9fc49e78c..2debb870bd0 100644
--- a/src/backend/access/nbtree/nbtxlog.c
+++ b/src/backend/access/nbtree/nbtxlog.c
@@ -997,9 +997,10 @@ btree_xlog_unlink_page(uint8 info, XLogRecPtr lsn, XLogRecord *record)
 		buffer = XLogReadBuffer(xlrec->node, xlrec->leafblk, true);
 		Assert(BufferIsValid(buffer));
 		page = (Page) BufferGetPage(buffer);
-		pageop = (BTPageOpaque) PageGetSpecialPointer(page);
 
 		_bt_pageinit(page, BufferGetPageSize(buffer));
+		pageop = (BTPageOpaque) PageGetSpecialPointer(page);
+
 		pageop->btpo_flags = BTP_HALF_DEAD | BTP_LEAF;
 		pageop->btpo_prev = xlrec->leafleftsib;
 		pageop->btpo_next = xlrec->leafrightsib;


[parent: 1afc1fe9c7bb]