Fix overflow in check_tile_extent() - #1635
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Within `Dimension::check_tile_extent<T>()`, the following variable has a type
deduction from `auto` to `uint64_t`:
auto upper_floor =
((range - 1) / (*tile_extent)) * (*tile_extent) + domain[0];
If `domain[0]` is negative, it may overflow the upper_floor. A trivial example
would be a domain with a range of [-10, -5] with a tile extent size of 5. The
above calculation comes out to -5, which overflows to (MAXINT64 - 5).
If we force the type of `upper_floor` to uint64_t, it solves the above issue
but causes overflow if the tile extent is an unsigned type with a domain
that overflows the uint64_t.
This patch adds both a path for unsigned and signed extent tile types. The
upper_floor type must match the sign of the extent tile type.
This also uncovered a bug in the unit-cppapi-datetimes.cc where the domain
exceeds the expanded upper bound but the check was a false-negative.
stavrospapadopoulos
approved these changes
May 5, 2020
stavrospapadopoulos
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Great catch, thanks!
Shelnutt2
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May 13, 2020
Within `Dimension::check_tile_extent<T>()`, the following variable has a type
deduction from `auto` to `uint64_t`:
auto upper_floor =
((range - 1) / (*tile_extent)) * (*tile_extent) + domain[0];
If `domain[0]` is negative, it may overflow the upper_floor. A trivial example
would be a domain with a range of [-10, -5] with a tile extent size of 5. The
above calculation comes out to -5, which overflows to (MAXINT64 - 5).
If we force the type of `upper_floor` to uint64_t, it solves the above issue
but causes overflow if the tile extent is an unsigned type with a domain
that overflows the uint64_t.
This patch adds both a path for unsigned and signed extent tile types. The
upper_floor type must match the sign of the extent tile type.
This also uncovered a bug in the unit-cppapi-datetimes.cc where the domain
exceeds the expanded upper bound but the check was a false-negative.
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Within
Dimension::check_tile_extent<T>(), the following variable has a typededuction from
autotouint64_t:auto upper_floor =
((range - 1) / (*tile_extent)) * (*tile_extent) + domain[0];
If
domain[0]is negative, it may overflow the upper_floor. A trivial examplewould be a domain with a range of [-10, -5] with a tile extent size of 5. The
above calculation comes out to -5, which overflows to (MAXINT64 - 5).
If we force the type of
upper_floorto uint64_t, it solves the above issuebut causes overflow if the tile extent is an unsigned type with a domain
that overflows the uint64_t.
This patch adds both a path for unsigned and signed extent tile types. The
upper_floor type must match the sign of the extent tile type.
This also uncovered a bug in the unit-cppapi-datetimes.cc where the domain
exceeds the expanded upper bound but the check was a false-negative.