Detect Julian-date overflow in timestamp[tz]_pl_interval.

We perform addition of the days field of an interval via
arithmetic on the Julian-date representation of the timestamp's date.
This step is subject to int32 overflow, and we also should not let
the Julian date become very negative, for fear of weird results from
j2date.  (In the timestamptz case, allow a Julian date of -1 to pass,
since it might convert back to zero after timezone rotation.)

The additions of the months and microseconds fields could also
overflow, of course.  However, I believe we need no additional
checks there; the existing range checks should catch such cases.
The difficulty here is that j2date's magic modular arithmetic could
produce something that looks like it's in-range.

Per bug #18313 from Christian Maurer.  This has been wrong for
a long time, so back-patch to all supported branches.

Discussion: https://postgr.es/m/18313-64d2c8952d81e84b@postgresql.org

diff --git a/src/backend/utils/adt/timestamp.c b/src/backend/utils/adt/timestamp.c
index fbc6bad20d6d6699ed551619cd13e2faa79659eb..b41a08878a09452067fac5605999009b97ceb276 100644 (file)
--- a/src/backend/utils/adt/timestamp.c
+++ b/src/backend/utils/adt/timestamp.c
@@ -2893,8 +2893,16 @@ timestamp_pl_interval(PG_FUNCTION_ARGS)
                                                (errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
                                                 errmsg("timestamp out of range")));
 
-                       /* Add days by converting to and from Julian */
-                       julian = date2j(tm->tm_year, tm->tm_mon, tm->tm_mday) + span->day;
+                       /*
+                        * Add days by converting to and from Julian.  We need an overflow
+                        * check here since j2date expects a non-negative integer input.
+                        */
+                       julian = date2j(tm->tm_year, tm->tm_mon, tm->tm_mday);
+                       if (pg_add_s32_overflow(julian, span->day, &julian) ||
+                               julian < 0)
+                               ereport(ERROR,
+                                               (errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+                                                errmsg("timestamp out of range")));
                        j2date(julian, &tm->tm_year, &tm->tm_mon, &tm->tm_mday);
 
                        if (tm2timestamp(tm, fsec, NULL, &timestamp) != 0)
@@ -3001,8 +3009,19 @@ timestamptz_pl_interval(PG_FUNCTION_ARGS)
                                                (errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
                                                 errmsg("timestamp out of range")));
 
-                       /* Add days by converting to and from Julian */
-                       julian = date2j(tm->tm_year, tm->tm_mon, tm->tm_mday) + span->day;
+                       /*
+                        * Add days by converting to and from Julian.  We need an overflow
+                        * check here since j2date expects a non-negative integer input.
+                        * In practice though, it will give correct answers for small
+                        * negative Julian dates; we should allow -1 to avoid
+                        * timezone-dependent failures, as discussed in timestamp.h.
+                        */
+                       julian = date2j(tm->tm_year, tm->tm_mon, tm->tm_mday);
+                       if (pg_add_s32_overflow(julian, span->day, &julian) ||
+                               julian < -1)
+                               ereport(ERROR,
+                                               (errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+                                                errmsg("timestamp out of range")));
                        j2date(julian, &tm->tm_year, &tm->tm_mon, &tm->tm_mday);
 
                        tz = DetermineTimeZoneOffset(tm, session_timezone);

diff --git a/src/test/regress/expected/horology.out b/src/test/regress/expected/horology.out
index 5f619891c5d6b34b2ccf36e3369759231c6e6f14..058b009eeeba42d2f6d8d2820b15d407a9fc484a 100644 (file)
--- a/src/test/regress/expected/horology.out
+++ b/src/test/regress/expected/horology.out
@@ -367,6 +367,8 @@ SELECT timestamp without time zone 'Jan 1, 4713 BC' + interval '109203489 days'
  Sun Dec 31 00:00:00 294276
 (1 row)
 
+SELECT timestamp without time zone '2000-01-01' - interval '2483590 days' AS "out of range";
+ERROR:  timestamp out of range
 SELECT timestamp without time zone '12/31/294276' - timestamp without time zone '12/23/1999' AS "106751991 Days";
   106751991 Days  
 ------------------
@@ -627,6 +629,8 @@ SELECT timestamp with time zone '1999-12-01' + interval '1 month - 1 second' AS
  Fri Dec 31 23:59:59 1999 PST
 (1 row)
 
+SELECT timestamp with time zone '2000-01-01' - interval '2483590 days' AS "out of range";
+ERROR:  timestamp out of range
 SELECT (timestamp with time zone 'today' = (timestamp with time zone 'yesterday' + interval '1 day')) as "True";
  True 
 ------

diff --git a/src/test/regress/sql/horology.sql b/src/test/regress/sql/horology.sql
index a9495718288ddd2cb50296cbea20772b2425d4a7..b647f63c2bae4b4b34775a28712f828fec881048 100644 (file)
--- a/src/test/regress/sql/horology.sql
+++ b/src/test/regress/sql/horology.sql
@@ -84,6 +84,7 @@ SELECT timestamp without time zone '1999-12-01' + interval '1 month - 1 second'
 SELECT timestamp without time zone 'Jan 1, 4713 BC' + interval '106000000 days' AS "Feb 23, 285506";
 SELECT timestamp without time zone 'Jan 1, 4713 BC' + interval '107000000 days' AS "Jan 20, 288244";
 SELECT timestamp without time zone 'Jan 1, 4713 BC' + interval '109203489 days' AS "Dec 31, 294276";
+SELECT timestamp without time zone '2000-01-01' - interval '2483590 days' AS "out of range";
 SELECT timestamp without time zone '12/31/294276' - timestamp without time zone '12/23/1999' AS "106751991 Days";
 
 -- Shorthand values
@@ -115,6 +116,7 @@ SELECT timestamp with time zone '1996-03-01' - interval '1 second' AS "Feb 29";
 SELECT timestamp with time zone '1999-03-01' - interval '1 second' AS "Feb 28";
 SELECT timestamp with time zone '2000-03-01' - interval '1 second' AS "Feb 29";
 SELECT timestamp with time zone '1999-12-01' + interval '1 month - 1 second' AS "Dec 31";
+SELECT timestamp with time zone '2000-01-01' - interval '2483590 days' AS "out of range";
 
 SELECT (timestamp with time zone 'today' = (timestamp with time zone 'yesterday' + interval '1 day')) as "True";
 SELECT (timestamp with time zone 'today' = (timestamp with time zone 'tomorrow' - interval '1 day')) as "True";