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C++: Fix an issue with cpp/suspicious-add-sizeof in BMN databases - #21514
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Pull request overview
This PR updates the cpp/suspicious-add-sizeof query to avoid spurious alerts in build-mode: none (BMN) databases when pointer base types are extracted as erroneous, and adds regression coverage plus a change note.
Changes:
- Treat
ErroneousTypepointer bases as “char/void-sized” for the purposes of suppressing suspicious+ sizeof(...)pointer arithmetic results. - Add a buildless test case that exercises extraction-with-errors scenarios and updates expected results accordingly.
- Add a C++ pack change note documenting the analysis behavior change for BMN databases.
Reviewed changes
Copilot reviewed 5 out of 5 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
| cpp/ql/src/Security/CWE/CWE-468/SuspiciousAddWithSizeof.ql | Expands the query’s “char/void pointer” exemption to include erroneous base types. |
| cpp/ql/test/query-tests/Security/CWE/CWE-468/semmle/SuspiciousAddWithSizeof/buildless.cpp | New buildless test TU (expects extractor errors) to cover erroneous-type pointer arithmetic cases. |
| cpp/ql/test/query-tests/Security/CWE/CWE-468/semmle/SuspiciousAddWithSizeof/test.cpp | Adds typedefs/prototype to support the buildless test scenario. |
| cpp/ql/test/query-tests/Security/CWE/CWE-468/semmle/SuspiciousAddWithSizeof/SuspiciousAddWithSizeof.expected | Updates expected results to include findings from the new buildless test file. |
| cpp/ql/src/change-notes/2026-03-19-suspicious-add-sizeof.md | Records the BMN false-positive fix as a minor analysis change. |
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…AddWithSizeof/buildless.cpp
jketema
approved these changes
Mar 19, 2026
jketema
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LGTM if both "regular" and BMN DCA are happy.
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Fix an issue with the
cpp/suspicious-add-sizeofquery in BMN databases. It's possible to have pointer arithmetic on a pointer tochar(oruint8_t) type extracted as pointer arithmetic on a pointer to error type. To avoid spurious results we should assume that this could be a char type and permit arithmetic withsizeof.