From 6efdb1d0f3ab0e95c7958078251efeb1956fe2dc Mon Sep 17 00:00:00 2001
From: Matthias van de Meent <matthias@neon.tech>
Date: Tue, 1 Oct 2024 18:37:59 +0200
Subject: [PATCH] Fix small memory accounting bug in libpagestore (#9223)

Found while searching for other issues in shared memory.

The bug should be benign, in that it over-allocates memory for this
struct, but doesn't allow for out-of-bounds writes.
---
 pgxn/neon/libpagestore.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pgxn/neon/libpagestore.c b/pgxn/neon/libpagestore.c
index 07a19a7114..6c6489277d 100644
--- a/pgxn/neon/libpagestore.c
+++ b/pgxn/neon/libpagestore.c
@@ -937,7 +937,7 @@ PagestoreShmemInit(void)
 
 	LWLockAcquire(AddinShmemInitLock, LW_EXCLUSIVE);
 	pagestore_shared = ShmemInitStruct("libpagestore shared state",
-									   PagestoreShmemSize(),
+									   sizeof(PagestoreShmemState),
 									   &found);
 	if (!found)
 	{