From 097e41439d69e11fb870e009b1ac64dda4f01c3d Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Thu, 22 Dec 2016 13:54:40 -0500
Subject: [PATCH] Fix broken error check in _hash_doinsert.
You can't just cast a HashMetaPage to a Page, because the meta page
data is stored after the page header, not at offset 0. Fortunately,
this didn't break anything because it happens to find hashm_bsize
at the offset at which it expects to find pd_pagesize_version, and
the values are close enough to the same that this works out.
Still, it's a bug, so back-patch to all supported versions.
Mithun Cy, revised a bit by me.
---
src/backend/access/hash/hashinsert.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/src/backend/access/hash/hashinsert.c b/src/backend/access/hash/hashinsert.c
index 59c4213f9c..4b022b5755 100644
--- a/src/backend/access/hash/hashinsert.c
+++ b/src/backend/access/hash/hashinsert.c
@@ -35,6 +35,7 @@ _hash_doinsert(Relation rel, IndexTuple itup)
BlockNumber blkno;
BlockNumber oldblkno;
bool retry;
+ Page metapage;
Page page;
HashPageOpaque pageopaque;
Size itemsz;
@@ -58,7 +59,8 @@ _hash_doinsert(Relation rel, IndexTuple itup)
restart_insert:
/* Read the metapage */
metabuf = _hash_getbuf(rel, HASH_METAPAGE, HASH_READ, LH_META_PAGE);
- metap = HashPageGetMeta(BufferGetPage(metabuf));
+ metapage = BufferGetPage(metabuf);
+ metap = HashPageGetMeta(metapage);
/*
* Check whether the item can fit on a hash page at all. (Eventually, we
@@ -67,11 +69,11 @@ restart_insert:
*
* XXX this is useless code if we are only storing hash keys.
*/
- if (itemsz > HashMaxItemSize((Page) metap))
+ if (itemsz > HashMaxItemSize(metapage))
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("index row size %zu exceeds hash maximum %zu",
- itemsz, HashMaxItemSize((Page) metap)),
+ itemsz, HashMaxItemSize(metapage)),
errhint("Values larger than a buffer page cannot be indexed.")));
oldblkno = InvalidBlockNumber;