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Don't call PageGetSpecialPointer() on page until it's been initialized.

author Heikki Linnakangas <heikki.linnakangas@iki.fi>

2015年6月30日 10:37:16 +0000 (13:37 +0300)

committer Heikki Linnakangas <heikki.linnakangas@iki.fi>

2015年6月30日 10:41:30 +0000 (13:41 +0300)

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 patch | blob | blame | history

diff --git a/src/backend/access/nbtree/nbtxlog.c b/src/backend/access/nbtree/nbtxlog.c

index 2f8586725a2d7609d002f243f7b432084171d2a5..da28e21d5cbd46655a287dcdf0b850b6676dc47d 100644 (file)

--- 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;

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