Hello,
Today, I compiled the master branch of Postgres with the following GCC
version:
gcc (GCC) 13.1.1 20230511 (Red Hat 13.1.1-2)
I got the following warning:
[701/2058] Compiling C object
src/backend/postgres_lib.a.p/access_transam_xlogrecovery.c.o
In function ‘recoveryStopsAfter’,
inlined from ‘PerformWalRecovery’ at
../src/backend/access/transam/xlogrecovery.c:1749:8:
../src/backend/access/transam/xlogrecovery.c:2756:42: warning: ‘recordXtime’
may be used uninitialized [-Wmaybe-uninitialized]
2756 | recoveryStopTime = recordXtime;
| ~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~
../src/backend/access/transam/xlogrecovery.c: In function ‘PerformWalRecovery’:
../src/backend/access/transam/xlogrecovery.c:2647:21: note: ‘recordXtime’ was
declared here
2647 | TimestampTz recordXtime;
| ^~~~~~~~~~~
Investigating this issue I see a potential assignment in
xlogrecovery.c:2715. Best I can tell the warning looks real. Similar
functions in this file seem to initialize recordXtime to 0. Attached is
a patch which does just that.
--
Tristan Partin
Neon (https://neon.tech)
From 74cc0fcd0570383d273f49dbc7d669caf7474453 Mon Sep 17 00:00:00 2001
From: Tristan Partin <tris...@neon.tech>
Date: Tue, 6 Jun 2023 09:22:56 -0500
Subject: [PATCH v1] Initialize potentially uninitialized memory in
xlogrecovery.c
Seems that in certain cases recordXtime might be used prior to
assignment.
---
src/backend/access/transam/xlogrecovery.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/backend/access/transam/xlogrecovery.c b/src/backend/access/transam/xlogrecovery.c
index 4883fcb512..becc2bda62 100644
--- a/src/backend/access/transam/xlogrecovery.c
+++ b/src/backend/access/transam/xlogrecovery.c
@@ -2644,7 +2644,7 @@ recoveryStopsAfter(XLogReaderState *record)
uint8 info;
uint8 xact_info;
uint8 rmid;
- TimestampTz recordXtime;
+ TimestampTz recordXtime = 0;
/*
* Ignore recovery target settings when not in archive recovery (meaning
--
--
Tristan Partin
Neon (https://neon.tech)
