From 9a75c19591bf8c1bb657978ad6c4add639daca23 Mon Sep 17 00:00:00 2001
From: Sofia Kopikova <s.kopikova@postgrespro.ru>
Date: Fri, 4 Oct 2024 13:48:49 +0300
Subject: [PATCH] PGPRO-11098 add null-pointer check to ptrack_set_init_lsn()
 function

When ptrack extension is added to shared_preload_libraries, but
ptrack.map size is 0, we may encounter segmantation fault when calling
ptrack_backup_checkpoint_request_hook() function. This commit adds
additional null-pointer checks to ptrack_set_init_lsn() function called
by ptrack_backup_checkpoint_request_hook() to avoid this segfault
---
 engine.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/engine.c b/engine.c
index f0c2f9b..dfd7c84 100644
--- a/engine.c
+++ b/engine.c
@@ -659,6 +659,10 @@ XLogRecPtr
 ptrack_set_init_lsn(void)
 {
 	XLogRecPtr new_lsn;
+
+	if (ptrack_map_size == 0 || ptrack_map == NULL)
+		return InvalidXLogRecPtr;
+
 	if (RecoveryInProgress())
 		new_lsn = GetXLogReplayRecPtr(NULL);
 	else