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Fix false positives for std::byte pointer scaling - #22933
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Reproduce #22929 with int-pointer arithmetic from std::byte storage using C-style casts and reinterpret_cast. Record the current false positives alongside the existing char-pointer coverage. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Treat std::byte source pointers like char and void buffers when checking pointer scaling, avoiding false positives for intentional typed indexing. Match only the standard byte enum and update both cast-style tests to expect no alerts. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Add a minor analysis note for the reduced false positives in suspicious pointer scaling when indexing std::byte buffers. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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October 29, 2026 11:34
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🟢 Approval recommended
No active review issues are identified, and the narrowly scoped change includes targeted regression coverage for the std::byte pointer-casting cases.
No open issues 🎉
What changed in this PR
Updates cpp/suspicious-pointer-scaling to avoid false positives when intentional typed indexing starts from a std::byte* buffer.
Changes:
- Exempts source pointers based on the qualified
std::byteenum. - Adds regression coverage for C-style casts and
reinterpret_cast. - Documents the analysis improvement in a change note.
| File | Description |
|---|---|
cpp/ql/test/query-tests/Security/CWE/CWE-468/semmle/IncorrectPointerScaling/test.cpp |
Adds coverage for conversions from std::byte* using both cast forms. |
cpp/ql/src/Security/CWE/CWE-468/IncorrectPointerScaling.ql |
Exempts qualified std::byte source pointers from suspicious pointer-scaling results. |
cpp/ql/src/change-notes/2026-10-29-suspicious-pointer-scaling-byte.md |
Documents the false-positive reduction. |
Review effort: Lite (auto)
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OpenTTD alerts that have disappeared from DCA indeed used |
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Summary
std::byte*source pointers fromcpp/suspicious-pointer-scaling, avoiding false positives for intentional typed indexing into byte buffers.reinterpret_cast, and document the analysis change.The exemption matches the standard
std::byteenum by qualified name. This is an enum by definition of the spec.std::byteshould be treated similar tochar, so should exempted here.Fixes #22929