Hello, The function timestamptz_to_str() in src/bin/pg_waldump/compat.c does not handle the case when localtime() returns NULL, which can happen for timestamps that are out of the supported time_t range on some platforms.
This patch adds a simple check for a NULL return value and ensures that the function returns a clear error string "(timestamp out of range)" instead of causing undefined behavior or a crash. Best regards, Eugeny Goryachev *Patch attached for Postgres 16.6:* >From b443fb1a5b3b0f0ffb419c2eb7a7375c9d5b990e Mon Sep 17 00:00:00 2001 From: Eugeny Goryachev <[email protected]> Date: Wed, 15 Oct 2025 12:41:10 +0400 Subject: [PATCH] Fix timestamptz_to_str() for out-of-range timestamps --- src/bin/pg_waldump/compat.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/src/bin/pg_waldump/compat.c b/src/bin/pg_waldump/compat.c index 2aca73f2e93..825311b1bd4 100644 --- a/src/bin/pg_waldump/compat.c +++ b/src/bin/pg_waldump/compat.c @@ -54,6 +54,12 @@ timestamptz_to_str(TimestampTz t) time_t result = (time_t) timestamptz_to_time_t(t); struct tm *ltime = localtime(&result); + if (!ltime) + { + strlcpy(buf, "(timestamp out of range)", sizeof(buf)); + return buf; + } + strftime(ts, sizeof(ts), "%Y-%m-%d %H:%M:%S", ltime); strftime(zone, sizeof(zone), "%Z", ltime); -- 2.43.0 https://www.postgresql.org/message-id/flat/EAB008E3-6B87-413F-BA39-22A6ED5DF0F6%40yesql.se#61ba59bee3872723d4cfe809638f039b
From b443fb1a5b3b0f0ffb419c2eb7a7375c9d5b990e Mon Sep 17 00:00:00 2001 From: Eugeny Goryachev <[email protected]> Date: Wed, 15 Oct 2025 12:41:10 +0400 Subject: [PATCH] Fix timestamptz_to_str() for out-of-range timestamps --- src/bin/pg_waldump/compat.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/src/bin/pg_waldump/compat.c b/src/bin/pg_waldump/compat.c index 2aca73f2e93..825311b1bd4 100644 --- a/src/bin/pg_waldump/compat.c +++ b/src/bin/pg_waldump/compat.c @@ -54,6 +54,12 @@ timestamptz_to_str(TimestampTz t) time_t result = (time_t) timestamptz_to_time_t(t); struct tm *ltime = localtime(&result); + if (!ltime) + { + strlcpy(buf, "(timestamp out of range)", sizeof(buf)); + return buf; + } + strftime(ts, sizeof(ts), "%Y-%m-%d %H:%M:%S", ltime); strftime(zone, sizeof(zone), "%Z", ltime); -- 2.43.0
