--- \dll\postgresql-12.0\a\backend\access\transam\xlog.c	Mon Sep 30 17:06:55 2019
+++ xlog.c	Fri Nov 22 13:57:17 2019
@@ -1861,7 +1861,7 @@
 	{
 		Assert(((XLogPageHeader) cachedPos)->xlp_magic == XLOG_PAGE_MAGIC);
 		Assert(((XLogPageHeader) cachedPos)->xlp_pageaddr == ptr - (ptr % XLOG_BLCKSZ));
-		return cachedPos + ptr % XLOG_BLCKSZ;
+		return ptr % XLOG_BLCKSZ;
 	}
 
 	/*