Hello ,
The patch is pretty trivial.
--
Best regards,
Dmitry mailto:pgsql-hack...@dima.nikitin.name
From 0ff6a234740d7a7d2bb9572271a1dbdfd4f45f39 Mon Sep 17 00:00:00 2001
From: Dmitry Nikitin <postgre...@dima.nikitin.name>
Date: Mon, 25 Nov 2024 10:31:53 +0300
Subject: [PATCH 1/2] Get rid off the "magic number"
---
src/include/storage/bufpage.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/include/storage/bufpage.h b/src/include/storage/bufpage.h
index 6222d46e53..390d04103e 100644
--- a/src/include/storage/bufpage.h
+++ b/src/include/storage/bufpage.h
@@ -367,7 +367,7 @@ PageGetItem(Page page, ItemId itemId)
* of items on the page.
*
* NOTE: if the page is not initialized (pd_lower == 0), we must
- * return zero to ensure sane behavior.
+ * return InvalidOffsetNumber to ensure sane behavior.
*/
static inline OffsetNumber
PageGetMaxOffsetNumber(Page page)
@@ -375,7 +375,7 @@ PageGetMaxOffsetNumber(Page page)
PageHeader pageheader = (PageHeader) page;
if (pageheader->pd_lower <= SizeOfPageHeaderData)
- return 0;
+ return InvalidOffsetNumber;
else
return (pageheader->pd_lower - SizeOfPageHeaderData) / sizeof(ItemIdData);
}
--
2.39.5
From a75592838b2c7a8a164397c74ce1e21feb32ce44 Mon Sep 17 00:00:00 2001
From: Dmitry Nikitin <postgre...@dima.nikitin.name>
Date: Mon, 25 Nov 2024 10:32:40 +0300
Subject: [PATCH 2/2] Add Assert to stop invalid values to pass on
PageGetMaxOffsetNumber() can legitimately return zero
(InvalidOffsetNumber) as an indication of error. However there are no
any checks against that. As a result, for exampe, subsequent
PageGetItemId() will be accessing an array at -1.
---
src/backend/access/gin/ginentrypage.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/src/backend/access/gin/ginentrypage.c b/src/backend/access/gin/ginentrypage.c
index 94ef951e14..193119ac22 100644
--- a/src/backend/access/gin/ginentrypage.c
+++ b/src/backend/access/gin/ginentrypage.c
@@ -236,6 +236,8 @@ getRightMostTuple(Page page)
{
OffsetNumber maxoff = PageGetMaxOffsetNumber(page);
+ Assert(OffsetNumberIsValid(maxoff));
+
return (IndexTuple) PageGetItem(page, PageGetItemId(page, maxoff));
}
--
2.39.5
