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Fix interval_mul() to not produce insane results.

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interval_mul() attempts to prevent its calculations from producing silly
results, but it forgot that zero times infinity yields NaN in IEEE
arithmetic.  Hence, a case like '1 second'::interval * 'infinity'::float8
produced a NaN for the months product, which didn't trigger the range
check, resulting in bogus and possibly platform-dependent output.

This isn't terribly obvious to the naked eye because if you try that
exact case, you get "interval out of range" which is what you expect
--- but if you look closer, the error is coming from interval_out not
interval_mul.  interval_mul has allowed a bogus value into the system.

Fix by adding isnan tests.

Noted while testing Vitaly Burovoy's fix for infinity input to
to_timestamp().  Given the lack of field complaints, I doubt this
is worth a back-patch.
This commit is contained in:
Tom Lane 2016-03-29 17:21:12 -04:00
parent e511d878f3
commit a898b409f6
1 changed files with 4 additions and 2 deletions
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6
src/backend/utils/adt/timestamp.c
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@ -3351,14 +3351,16 @@ interval_mul(PG_FUNCTION_ARGS)
result = (Interval *) palloc(sizeof(Interval));
result_double = span->month * factor;
if (result_double > INT_MAX || result_double < INT_MIN)
if (isnan(result_double) ||
result_double > INT_MAX || result_double < INT_MIN)
ereport(ERROR,
(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
errmsg("interval out of range")));
result->month = (int32) result_double;
result_double = span->day * factor;
if (result_double > INT_MAX || result_double < INT_MIN)
if (isnan(result_double) ||
result_double > INT_MAX || result_double < INT_MIN)
ereport(ERROR,
(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
errmsg("interval out of range")));