From: Michael Paquier <michael@paquier.xyz>
Date: Wed, 10 Jul 2019 06:15:29 +0000 (+0900)
Subject: Fix variable initialization when using buffering build with GiST
X-Git-Tag: REL9_4_24~23
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=7b60468fa14ac8b65ba91f2dc3c2df11361d4be3;p=thirdparty%2Fpostgresql.git

Fix variable initialization when using buffering build with GiST

This can cause valgrind to complain, as the flag marking a buffer as a
temporary copy was not getting initialized.

While on it, fill in with zeros newly-created buffer pages.  This does
not matter when loading a block from a temporary file, but it makes the
push of an index tuple into a new buffer page safer.

This has been introduced by 1d27dcf, so backpatch all the way down to
9.4.

Author: Alexander Lakhin
Discussion: https://postgr.es/m/15899-0d24fb273b3dd90c@postgresql.org
Backpatch-through: 9.4
---

diff --git a/src/backend/access/gist/gistbuildbuffers.c b/src/backend/access/gist/gistbuildbuffers.c
index 577ea613b11..b92052eddb3 100644
--- a/src/backend/access/gist/gistbuildbuffers.c
+++ b/src/backend/access/gist/gistbuildbuffers.c
@@ -140,6 +140,7 @@ gistGetNodeBuffer(GISTBuildBuffers *gfbb, GISTSTATE *giststate,
 		nodeBuffer->pageBlocknum = InvalidBlockNumber;
 		nodeBuffer->pageBuffer = NULL;
 		nodeBuffer->queuedForEmptying = false;
+		nodeBuffer->isTemp = false;
 		nodeBuffer->level = level;
 
 		/*
@@ -188,8 +189,8 @@ gistAllocateNewPageBuffer(GISTBuildBuffers *gfbb)
 {
 	GISTNodeBufferPage *pageBuffer;
 
-	pageBuffer = (GISTNodeBufferPage *) MemoryContextAlloc(gfbb->context,
-														   BLCKSZ);
+	pageBuffer = (GISTNodeBufferPage *) MemoryContextAllocZero(gfbb->context,
+															   BLCKSZ);
 	pageBuffer->prev = InvalidBlockNumber;
 
 	/* Set page free space */