Fix variable initialization when using buffering build with GiST

michaelpq · michaelpq · commit 7b60468fa14a · 2019-07-10T15:15:29.000+09:00
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
@@ -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 */
