fix(qdp): guard batch size multiplication against overflow#1324
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`Preprocessor::validate_batch` and `AmplitudeEncoder::encode_batch_f32` computed `num_samples * sample_size` without overflow checks, while the analogous angle encoder paths already use `checked_mul`. On 64-bit hosts the product can wrap and let an undersized buffer pass validation, leading to out-of-bounds reads in the encoder. Mirror the angle.rs pattern: use `checked_mul` and surface an `InvalidInput` error on overflow. Add a unit test covering the overflow path through the shared preprocessor.
rich7420
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ryankert01
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ryankert01
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May 18, 2026
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Make sense, will let copilot double check for me. |
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Pull request overview
This PR hardens QDP batch validation by preventing unchecked usize multiplication overflow when deriving expected batch buffer sizes, aligning amplitude/preprocessing behavior with existing checked length validation patterns.
Changes:
- Added
checked_muloverflow handling inPreprocessor::validate_batch. - Added matching overflow handling in
AmplitudeEncoder::encode_batch_f32. - Added a unit test for the preprocessing overflow path.
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
qdp/qdp-core/src/preprocessing.rs |
Guards batch expected-length calculation and tests overflow rejection. |
qdp/qdp-core/src/gpu/encodings/amplitude.rs |
Guards f32 amplitude batch expected-length calculation before length comparison. |
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ryankert01
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May 20, 2026
`Preprocessor::validate_batch` and `AmplitudeEncoder::encode_batch_f32` computed `num_samples * sample_size` without overflow checks, while the analogous angle encoder paths already use `checked_mul`. On 64-bit hosts the product can wrap and let an undersized buffer pass validation, leading to out-of-bounds reads in the encoder. Mirror the angle.rs pattern: use `checked_mul` and surface an `InvalidInput` error on overflow. Add a unit test covering the overflow path through the shared preprocessor.
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Summary
Preprocessor::validate_batchandAmplitudeEncoder::encode_batch_f32computednum_samples * sample_sizewithout overflow checks. The angle encoder paths already usechecked_mul(angle.rs:87, :143, :327, :405, :528) — these two sites were missed.checked_mulreturningMahoutError::InvalidInputon overflow.Changes
qdp/qdp-core/src/preprocessing.rs: guardnum_samples * sample_sizeinvalidate_batch.qdp/qdp-core/src/gpu/encodings/amplitude.rs: guard the same multiplication inencode_batch_f32(the f64 path already routes throughPreprocessor::validate_batch).preprocessing.rscovering the overflow path.Test plan
cargo test --manifest-path qdp/qdp-core/Cargo.toml --lib— 77 passed, 0 failedvalidate_batch_rejects_size_overflowexercises thechecked_mulfailure branch