ORC-2166: [C++] Guard C++ integer arithmetic against overflow#2622
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ffacs wants to merge 3 commits into
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ORC-2166: [C++] Guard C++ integer arithmetic against overflow#2622ffacs wants to merge 3 commits into
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| hasNegativeLength |= value < 0; | ||
| size_t length = static_cast<size_t>(value); | ||
| size_t nextTotalLength = totalLength + length; | ||
| hasLengthOverflow |= nextTotalLength < totalLength; |
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Like skip() method, shall we throw here instead of waiting for the whole loop is finished?
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Pull request overview
This PR introduces reusable checked integer arithmetic helpers in the C++ codebase and applies them across multiple reader/allocation paths to prevent integer overflow from malformed ORC input (failing fast instead of wrapping into unsafe sizes/offsets).
Changes:
- Add
addWithOverflow/multiplyWithOverflowhelpers and unit tests for overflow behavior. - Harden reader logic (string/list/map/union/dictionary paths) against negative lengths and overflowing length accumulation.
- Add overflow-safe sizing logic for vector offsets,
DataBufferallocation sizing, and block buffer size/capacity calculations.
Reviewed changes
Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| c++/test/TestUtils.cc | Adds unit tests for the new overflow helper functions. |
| c++/test/TestColumnReader.cc | Adds regression tests for rejecting negative/overflowing length streams (string/list/map). |
| c++/test/meson.build | Wires the new test source into the Meson test build. |
| c++/test/CMakeLists.txt | Wires the new test source into the CMake test build. |
| c++/src/Vector.cc | Uses checked arithmetic when sizing list/map offset buffers (cap + 1). |
| c++/src/Utils.hh | Introduces reusable checked add/multiply helpers for integral types. |
| c++/src/MemoryPool.cc | Adds checked sizing for DataBuffer allocations and zeroing. |
| c++/src/DictionaryLoader.cc | Guards dictionary blob reads and dictionary offset accumulation against overflow/negative values. |
| c++/src/ColumnReader.cc | Adds overflow/negative-length guards for string direct, list/map length accumulation, union child counts, and double skip sizing. |
| c++/src/BlockBuffer.hh | Avoids potential overflow in getBlockNumber() computation. |
| c++/src/BlockBuffer.cc | Uses checked arithmetic for block buffer size/capacity growth. |
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| uint64_t nextBlockNumber = currentSize_ / blockSize_ + 1; | ||
| uint64_t nextSize = 0; | ||
| if (multiplyWithOverflow(nextBlockNumber, blockSize_, &nextSize)) { |
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| auto addLength = [&](int64_t value) { | ||
| if (value < 0) { | ||
| hasNegativeLength = true; | ||
| return; | ||
| } | ||
| size_t length = static_cast<size_t>(value); | ||
| size_t nextTotalLength = 0; | ||
| bool overflow = addWithOverflow(totalLength, length, &nextTotalLength); | ||
| hasLengthOverflow |= overflow; |
wgtmac
reviewed
May 26, 2026
| uint64_t checkedBufferSize(uint64_t count) { | ||
| uint64_t bytes = 0; | ||
| if (multiplyWithOverflow(static_cast<uint64_t>(sizeof(T)), count, &bytes)) { | ||
| throw std::length_error("DataBuffer allocation size overflow"); |
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Do we want to define a orc-specific exception that derives from orc::Exception? arrow-cpp catches all orc::Exception to avoid crashing.
wgtmac
reviewed
May 26, 2026
| if (newBlockPtr != nullptr) { | ||
| blocks_.push_back(newBlockPtr); | ||
| currentCapacity_ += blockSize_; | ||
| try { |
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Why do we need this try-catch block?
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What changes were proposed in this pull request?
This PR adds reusable checked integer arithmetic helpers for the C++ code:
addWithOverflowandmultiplyWithOverflow.The patch uses these helpers to reject overflow-prone arithmetic in reader and buffer paths, including direct string length accumulation, list/map length accumulation, dictionary offsets, float/double skip byte counts, union child counts,
DataBufferallocation sizes,BlockBuffersize/capacity calculations, and list/map vector offset capacity calculations.Regression tests were added for the overflow helpers and malformed string/list/map length streams.
Why are the changes needed?
Malformed ORC files can provide invalid or extremely large values in length streams. Negative lengths or overflowing length sums can cause unchecked integer wraparound, incorrectly sized allocations, wrapped offsets, or unsafe skip/copy behavior.
Centralizing checked arithmetic makes these cases fail cleanly before unsafe allocation or memory access. Reader-facing malformed input now fails with
ParseError.How was this patch tested?
Ran the full C++ test target:
Result:
1/2 Test #1: orc-test .... Passed
2/2 Test #2: tool-test .... Passed
100% tests passed, 0 tests failed out of 2
Also ran targeted tests during development for the new overflow checks.
Was this patch authored or co-authored using generative AI tooling?
Yes. Generated with OpenAI Codex.