[PATCH][BUG FIX] Pointer arithmetic with NULL - Mailing list pgsql-hackers

Hi,
Pointer addition with NULL, is technically undefined behavior.

Best regards.
Ranier Vilela

--- \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;
     }

     /*