On Thu, Feb 16, 2023 at 1:12 AM Tom Lane wrote:
> Yeah, I don't think this would create a performance problem, at least not
> if you're using a compiler that implements pg_sub_s64_overflow reasonably.
> (And if you're not, and this bugs you, the answer is to get a better
Please find attached the v2 of the said patch with the tests added. I
tested and it applies with all tests passing both on REL_14_STABLE,
REL_15_STABLE and master. I don't know how the decision on
backpatching is made and whether it makes sense here or not. If any
additional work is required, please let me know.
> By chance did you look at all other nearby cases, is it the only place
> with overflow?
Not really, no. The other place where it could overflow was in the
interval justification function and it was fixed about a year ago.
That wasn't backpatched afaict. See
https://postgr.es/m/caavxfhenqsj2xyfbpuf_8nnquijqkag04nw6abqq0dbzsxf...@mail.gmail.com
Regards,
Nick
From 52d49e90b73d13c9acfd2b85f1ae38dfb0f64f9d Mon Sep 17 00:00:00 2001
From: Nick Babadzhanian
Date: Thu, 16 Feb 2023 13:38:34 +0100
Subject: [PATCH] Address interval overflow and add corresponding tests
---
src/backend/utils/adt/timestamp.c | 6 +-
src/test/regress/expected/interval.out | 9 +
src/test/regress/sql/interval.sql | 4
3 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
index f70f829d83..3ff51102a8 100644
--- a/src/backend/utils/adt/timestamp.c
+++ b/src/backend/utils/adt/timestamp.c
@@ -2688,7 +2688,11 @@ timestamp_mi(PG_FUNCTION_ARGS)
(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
errmsg("cannot subtract infinite timestamps")));
- result->time = dt1 - dt2;
+ /* Subtract dt1 and dt2 with overflow detection */
+ if (unlikely(pg_sub_s64_overflow(dt1, dt2, >time)))
+ ereport(ERROR,
+(errcode(ERRCODE_INTERVAL_FIELD_OVERFLOW),
+ errmsg("interval field out of range")));
result->month = 0;
result->day = 0;
diff --git a/src/test/regress/expected/interval.out b/src/test/regress/expected/interval.out
index 78c1fab2b6..280f25c218 100644
--- a/src/test/regress/expected/interval.out
+++ b/src/test/regress/expected/interval.out
@@ -235,6 +235,15 @@ LINE 1: INSERT INTO INTERVAL_TBL_OF (f1) VALUES ('-2147483648 years'...
-- Test edge-case overflow detection in interval multiplication
select extract(epoch from '256 microseconds'::interval * (2^55)::float8);
ERROR: interval out of range
+-- Test edge-case overflow in timestamp[tz] subtraction
+SELECT timestamptz'294276-12-31 23:59:59 UTC' - timestamptz'1999-12-23 19:59:04.224193 UTC' AS doesnt_overflow;
+doesnt_overflow
+
+ 106751991 days 04:00:54.775807
+(1 row)
+
+SELECT timestamptz'294276-12-31 23:59:59 UTC' - timestamptz'1999-12-23 19:59:04.224192 UTC' AS overflows;
+ERROR: interval field out of range
SELECT r1.*, r2.*
FROM INTERVAL_TBL_OF r1, INTERVAL_TBL_OF r2
WHERE r1.f1 > r2.f1
diff --git a/src/test/regress/sql/interval.sql b/src/test/regress/sql/interval.sql
index 55a449b617..a228cf1445 100644
--- a/src/test/regress/sql/interval.sql
+++ b/src/test/regress/sql/interval.sql
@@ -76,6 +76,10 @@ INSERT INTO INTERVAL_TBL_OF (f1) VALUES ('-2147483648 years');
-- Test edge-case overflow detection in interval multiplication
select extract(epoch from '256 microseconds'::interval * (2^55)::float8);
+-- Test edge-case overflow in timestamp[tz] subtraction
+SELECT timestamptz'294276-12-31 23:59:59 UTC' - timestamptz'1999-12-23 19:59:04.224193 UTC' AS doesnt_overflow;
+SELECT timestamptz'294276-12-31 23:59:59 UTC' - timestamptz'1999-12-23 19:59:04.224192 UTC' AS overflows;
+
SELECT r1.*, r2.*
FROM INTERVAL_TBL_OF r1, INTERVAL_TBL_OF r2
WHERE r1.f1 > r2.f1
--
2.39.1
