From fdf28853ae6a397497b79fea69f89f4f7b9aa991 Mon Sep 17 00:00:00 2001 From: Heikki Linnakangas Date: Tue, 30 Jun 2015 13:37:16 +0300 Subject: [PATCH] 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 2f8586725a..da28e21d5c 100644 --- a/src/backend/access/nbtree/nbtxlog.c +++ b/src/backend/access/nbtree/nbtxlog.c @@ -864,9 +864,10 @@ btree_xlog_unlink_page(uint8 info, XLogReaderState *record) buffer = XLogInitBufferForRedo(record, 3); 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;