Bug/2220 array subscript out of range exception can be thrown under a floating point rounding edge case #2227
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Code incorrectly deals with edge cases where atan2() returns end of range [-pi, pi] Signed-off-by: Kevin Wheatley <kevin.wheatley@framestore.com>
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Just to note whatever the solution it should probably be back ported to 2.4.x branch. Something to discuss in next TSC |
…ion to not over flow table bounds during lookup All tables are now 1 entry larger and should have valid data wrapped into the extra entries Signed-off-by: Kevin Wheatley <kevin.wheatley@framestore.com>
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Pull request overview
This PR fixes an array subscript out of range exception in the ACES2 output transform that can occur due to floating-point rounding edge cases when hue angles are near the boundary of the 360-degree hue range. The fix adds an additional entry at the upper wrap boundary of internal lookup tables to ensure interpolation never accesses memory beyond the allocated array.
Key Changes:
- Modified table size calculation to add an extra upper boundary entry
- Updated four table initialization functions to populate the new boundary entry
- Added a regression test case that reproduces the edge case from issue #2220
Reviewed changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.
| File | Description |
|---|---|
src/OpenColorIO/ops/fixedfunction/ACES2/Common.h |
Modified TableBase struct to increase total table size from nominal_size + 2 to nominal_size + 3 entries by splitting the addition constants |
src/OpenColorIO/ops/fixedfunction/ACES2/Transform.cpp |
Updated four table builder functions (build_hue_table, build_cusp_table, make_reach_m_table, make_upper_hull_gamma) to populate the new upper_wrap_index + 1 entry with wrapped values for continuity |
tests/cpu/ops/fixedfunction/FixedFunctionOpCPU_tests.cpp |
Added new test case aces_ot_20_edge_cases with specific RGB values that trigger the boundary condition |
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…cess bug Signed-off-by: Kevin Wheatley <kevin.wheatley@framestore.com>
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Reproduced #2220
Using Debug build on Windows 11 using VS 2022 Community edition:
Fix is to add an additional entry at the end of the tables, to handle the boundary condition due to atan2() returning the interval [-pi, +pi] each new entry filled with the corresponding entry from the lower entries to maintain continuity