From a891ff3c36a9dfff48d954c6e4fbfb5ddae181f6 Mon Sep 17 00:00:00 2001 From: Baji Shaik Date: Fri, 3 Jul 2026 18:47:46 -0500 Subject: [PATCH v6] Reject infinite and out-of-range interval shifts in uuidv7(). uuidv7(interval) shifts the current time by the given interval before encoding it into the 48-bit Unix-millisecond timestamp field of the generated UUID. Two cases were mishandled: An infinite interval ('infinity' or '-infinity') produced an infinite timestamp, which overflowed during the conversion to Unix-epoch microseconds and yielded a garbage UUID. Reject infinite intervals up front, before any timestamp arithmetic. A shift that moved the timestamp outside the range representable by the 48-bit field was silently accepted. Timestamps before the Unix epoch wrapped when cast to unsigned, and timestamps beyond approximately year 10889 overflowed the field; both produced UUIDs with bogus timestamps that break sort ordering. Reject any shifted timestamp outside the supported range. Also document that infinite intervals and out-of-range shifts are rejected. Although raising a new error changes behavior in a stable branch, this is back-patched to 18 (where uuidv7(interval) was introduced) because the previous behavior can silently corrupt data. Failing loudly is far safer than silently accepting the wraparound; otherwise users may not discover that their UUIDv7 values are no longer sortable until years later, when recovery is painful. It also matches how PostgreSQL already handles timestamp + interval overflow, which raises an error. The change only affects applications passing an interval large enough to push the result outside the representable range. Backpatch to 18, where uuidv7(interval) was introduced. Reported-by: Christophe Pettus Author: Baji Shaik Reviewed-by: Masahiko Sawada Reviewed-by: Zsolt Parragi Reviewed-by: Tristan Partin Reviewed-by: Kyotaro Horiguchi Discussion: https://www.postgresql.org/message-id/799A70FA-6E5C-4118-99EB-2FBBE1CBAC54@thebuild.com Backpatch-through: 18 --- doc/src/sgml/func/func-uuid.sgml | 6 ++++ src/backend/utils/adt/uuid.c | 45 ++++++++++++++++++++++++++---- src/test/regress/expected/uuid.out | 22 +++++++++++++++ src/test/regress/sql/uuid.sql | 13 +++++++++ 4 files changed, 80 insertions(+), 6 deletions(-) diff --git a/doc/src/sgml/func/func-uuid.sgml b/doc/src/sgml/func/func-uuid.sgml index 2638e2bf85..89fd5781bc 100644 --- a/doc/src/sgml/func/func-uuid.sgml +++ b/doc/src/sgml/func/func-uuid.sgml @@ -82,6 +82,12 @@ sub-millisecond timestamp + random. The optional parameter shift will shift the computed timestamp by the given interval. + Infinite interval values are not accepted. + The shifted timestamp must fall within the range supported by + UUID version 7's 48-bit millisecond timestamp field: from + 1970-01-01 00:00:00 UTC to approximately year 10889. + An error is raised if the resulting timestamp is outside this + range. uuidv7() diff --git a/src/backend/utils/adt/uuid.c b/src/backend/utils/adt/uuid.c index 2d33ba2640..a9edceabab 100644 --- a/src/backend/utils/adt/uuid.c +++ b/src/backend/utils/adt/uuid.c @@ -33,6 +33,23 @@ #define NS_PER_US INT64CONST(1000) #define US_PER_MS INT64CONST(1000) +/* + * The offset between the PostgreSQL epoch (2000-01-01) and the Unix epoch + * (1970-01-01) in microseconds. Subtract this from a Unix-epoch microseconds + * to get a TimestampTz. + */ +#define PG_UNIX_EPOCH_OFFSET_US \ + ((int64) (POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY * USECS_PER_SEC) + +/* + * Valid timestamp range for UUID version 7, expressed in PostgreSQL-epoch + * microseconds. UUIDv7 uses a 48-bit unsigned millisecond field relative + * to the Unix epoch, so the representable window is [1970-01-01, ~10889]. + */ +#define UUIDV7_MIN_TIMESTAMP (-PG_UNIX_EPOCH_OFFSET_US) +#define UUIDV7_MAX_TIMESTAMP \ + (((INT64CONST(1) << 48) - 1) * US_PER_MS - PG_UNIX_EPOCH_OFFSET_US) + /* * UUID version 7 uses 12 bits in "rand_a" to store 1/4096 (or 2^12) fractions of * sub-millisecond. While most Unix-like platforms provide nanosecond-precision @@ -690,6 +707,13 @@ uuidv7_interval(PG_FUNCTION_ARGS) int64 ns = get_real_time_ns_ascending(); int64 us; + /* Reject infinite intervals before any arithmetic */ + if (INTERVAL_NOT_FINITE(shift)) + ereport(ERROR, + (errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE), + errmsg("interval out of range for UUID version 7"), + errdetail("UUID version 7 does not support infinite intervals."))); + /* * Shift the current timestamp by the given interval. To calculate time * shift correctly, we convert the UNIX epoch to TimestampTz and use @@ -697,16 +721,26 @@ uuidv7_interval(PG_FUNCTION_ARGS) * precision. */ - ts = (TimestampTz) (ns / NS_PER_US) - - (POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY * USECS_PER_SEC; + ts = (TimestampTz) (ns / NS_PER_US) - PG_UNIX_EPOCH_OFFSET_US; /* Compute time shift */ ts = DatumGetTimestampTz(DirectFunctionCall2(timestamptz_pl_interval, TimestampTzGetDatum(ts), IntervalPGetDatum(shift))); - /* Convert a TimestampTz value back to an UNIX epoch timestamp */ - us = ts + (POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY * USECS_PER_SEC; + /* + * Reject timestamps outside the range representable by UUID version 7's + * 48-bit millisecond field. We compare in PostgreSQL-epoch units so that + * the subsequent conversion to Unix-epoch microseconds cannot overflow. + */ + if (ts < UUIDV7_MIN_TIMESTAMP || ts > UUIDV7_MAX_TIMESTAMP) + ereport(ERROR, + (errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE), + errmsg("timestamp out of range for UUID version 7"), + errdetail("UUID version 7 supports timestamps from 1970-01-01 to approximately year 10889."))); + + /* Convert the TimestampTz value to a Unix-epoch timestamp in usec */ + us = ts + PG_UNIX_EPOCH_OFFSET_US; /* Generate an UUIDv7 */ uuid = generate_uuidv7(us / US_PER_MS, (us % US_PER_MS) * NS_PER_US + ns % NS_PER_US); @@ -766,8 +800,7 @@ uuid_extract_timestamp(PG_FUNCTION_ARGS) + (((uint64) uuid->data[0]) << 40); /* convert ms to us, then adjust */ - ts = (TimestampTz) (tms * US_PER_MS) - - (POSTGRES_EPOCH_JDATE - UNIX_EPOCH_JDATE) * SECS_PER_DAY * USECS_PER_SEC; + ts = (TimestampTz) (tms * US_PER_MS) - PG_UNIX_EPOCH_OFFSET_US; PG_RETURN_TIMESTAMPTZ(ts); } diff --git a/src/test/regress/expected/uuid.out b/src/test/regress/expected/uuid.out index cd7cd8b711..36d54d2f33 100644 --- a/src/test/regress/expected/uuid.out +++ b/src/test/regress/expected/uuid.out @@ -268,6 +268,28 @@ SELECT y, ts, prev_ts FROM uuidts WHERE ts < prev_ts; ---+----+--------- (0 rows) +-- uuidv7: infinite intervals are rejected +SELECT uuidv7('infinity'::interval); +ERROR: interval out of range for UUID version 7 +DETAIL: UUID version 7 does not support infinite intervals. +SELECT uuidv7('-infinity'::interval); +ERROR: interval out of range for UUID version 7 +DETAIL: UUID version 7 does not support infinite intervals. +-- uuidv7: timestamps before Unix epoch are rejected +SELECT uuidv7('-1000 years'::interval); +ERROR: timestamp out of range for UUID version 7 +DETAIL: UUID version 7 supports timestamps from 1970-01-01 to approximately year 10889. +-- uuidv7: timestamps beyond 48-bit ms field (~year 10889) are rejected +SELECT uuidv7('9000 years'::interval); +ERROR: timestamp out of range for UUID version 7 +DETAIL: UUID version 7 supports timestamps from 1970-01-01 to approximately year 10889. +-- uuidv7: a large but in-range forward shift is accepted +SELECT uuid_extract_timestamp(uuidv7('1000 years'::interval)) > now() + '999 years'::interval; + ?column? +---------- + t +(1 row) + -- extract functions -- version SELECT uuid_extract_version('11111111-1111-5111-8111-111111111111'); -- 5 diff --git a/src/test/regress/sql/uuid.sql b/src/test/regress/sql/uuid.sql index d0481a1502..944be956df 100644 --- a/src/test/regress/sql/uuid.sql +++ b/src/test/regress/sql/uuid.sql @@ -143,6 +143,19 @@ WITH uuidts AS ( ) SELECT y, ts, prev_ts FROM uuidts WHERE ts < prev_ts; +-- uuidv7: infinite intervals are rejected +SELECT uuidv7('infinity'::interval); +SELECT uuidv7('-infinity'::interval); + +-- uuidv7: timestamps before Unix epoch are rejected +SELECT uuidv7('-1000 years'::interval); + +-- uuidv7: timestamps beyond 48-bit ms field (~year 10889) are rejected +SELECT uuidv7('9000 years'::interval); + +-- uuidv7: a large but in-range forward shift is accepted +SELECT uuid_extract_timestamp(uuidv7('1000 years'::interval)) > now() + '999 years'::interval; + -- extract functions -- version -- 2.54.0