Guard against overflow in make_interval().

The original code did very little to guard against integer or floating
point overflow when computing the interval's fields.  Detect any such
overflows and error out, rather than silently returning bogus results.

Joseph Koshakow, reviewed by Ashutosh Bapat and me.

Discussion: https://postgr.es/m/CAAvxfHcm1TPwH_zaGWuFoL8pZBestbRZTU6Z%3D-RvAdSXTPbKfg%40mail.gmail.com

src/backend/utils/adt/timestamp.c

@@ -1509,24 +1509,41 @@ make_interval(PG_FUNCTION_ARGS)
 	Interval   *result;
 
 	/*
-	 * Reject out-of-range inputs.  We really ought to check the integer
-	 * inputs as well, but it's not entirely clear what limits to apply.
+	 * Reject out-of-range inputs.  We reject any input values that cause
+	 * integer overflow of the corresponding interval fields.
 	 */
 	if (isinf(secs) || isnan(secs))
-		ereport(ERROR,
-				(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
-				 errmsg("interval out of range")));
+		goto out_of_range;
 
 	result = (Interval *) palloc(sizeof(Interval));
-	result->month = years * MONTHS_PER_YEAR + months;
-	result->day = weeks * 7 + days;
 
-	secs = rint(secs * USECS_PER_SEC);
-	result->time = hours * ((int64) SECS_PER_HOUR * USECS_PER_SEC) +
-		mins * ((int64) SECS_PER_MINUTE * USECS_PER_SEC) +
-		(int64) secs;
+	/* years and months -> months */
+	if (pg_mul_s32_overflow(years, MONTHS_PER_YEAR, &result->month) ||
+		pg_add_s32_overflow(result->month, months, &result->month))
+		goto out_of_range;
+
+	/* weeks and days -> days */
+	if (pg_mul_s32_overflow(weeks, DAYS_PER_WEEK, &result->day) ||
+		pg_add_s32_overflow(result->day, days, &result->day))
+		goto out_of_range;
+
+	/* hours and mins -> usecs (cannot overflow 64-bit) */
+	result->time = hours * USECS_PER_HOUR + mins * USECS_PER_MINUTE;
+
+	/* secs -> usecs */
+	secs = rint(float8_mul(secs, USECS_PER_SEC));
+	if (!FLOAT8_FITS_IN_INT64(secs) ||
+		pg_add_s64_overflow(result->time, (int64) secs, &result->time))
+		goto out_of_range;
 
 	PG_RETURN_INTERVAL_P(result);
+
+out_of_range:
+	ereport(ERROR,
+			errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+			errmsg("interval out of range"));
+
+	PG_RETURN_NULL();			/* keep compiler quiet */
 }
 
 /* EncodeSpecialTimestamp()

src/include/datatype/timestamp.h

@@ -114,6 +114,7 @@ struct pg_itm_in
  *	30 days.
  */
 #define DAYS_PER_MONTH	30		/* assumes exactly 30 days per month */
+#define DAYS_PER_WEEK	7
 #define HOURS_PER_DAY	24		/* assume no daylight savings time changes */
 
 /*

src/test/regress/expected/interval.out

@@ -1587,6 +1587,33 @@ select interval '-2147483648 months -2147483648 days -9223372036854775808 micros
 ERROR:  interval field value out of range: "-2147483648 months -2147483648 days -9223372036854775808 microseconds ago"
 LINE 1: select interval '-2147483648 months -2147483648 days -922337...
                         ^
+-- overflowing using make_interval
+select make_interval(years := 178956971);
+ERROR:  interval out of range
+select make_interval(years := -178956971);
+ERROR:  interval out of range
+select make_interval(years := 1, months := 2147483647);
+ERROR:  interval out of range
+select make_interval(years := -1, months := -2147483648);
+ERROR:  interval out of range
+select make_interval(weeks := 306783379);
+ERROR:  interval out of range
+select make_interval(weeks := -306783379);
+ERROR:  interval out of range
+select make_interval(weeks := 1, days := 2147483647);
+ERROR:  interval out of range
+select make_interval(weeks := -1, days := -2147483648);
+ERROR:  interval out of range
+select make_interval(secs := 1e308);
+ERROR:  value out of range: overflow
+select make_interval(secs := 1e18);
+ERROR:  interval out of range
+select make_interval(secs := -1e18);
+ERROR:  interval out of range
+select make_interval(mins := 1, secs := 9223372036800.0);
+ERROR:  interval out of range
+select make_interval(mins := -1, secs := -9223372036800.0);
+ERROR:  interval out of range
 -- test that INT_MIN number is formatted properly
 SET IntervalStyle to postgres;
 select interval '-2147483648 months -2147483648 days -9223372036854775808 us';

src/test/regress/sql/interval.sql

@@ -511,6 +511,21 @@ select interval '-2147483648 days ago';
 select interval '-9223372036854775808 microseconds ago';
 select interval '-2147483648 months -2147483648 days -9223372036854775808 microseconds ago';
 
+-- overflowing using make_interval
+select make_interval(years := 178956971);
+select make_interval(years := -178956971);
+select make_interval(years := 1, months := 2147483647);
+select make_interval(years := -1, months := -2147483648);
+select make_interval(weeks := 306783379);
+select make_interval(weeks := -306783379);
+select make_interval(weeks := 1, days := 2147483647);
+select make_interval(weeks := -1, days := -2147483648);
+select make_interval(secs := 1e308);
+select make_interval(secs := 1e18);
+select make_interval(secs := -1e18);
+select make_interval(mins := 1, secs := 9223372036800.0);
+select make_interval(mins := -1, secs := -9223372036800.0);
+
 -- test that INT_MIN number is formatted properly
 SET IntervalStyle to postgres;
 select interval '-2147483648 months -2147483648 days -9223372036854775808 us';