C++: Fix FP in cpp/overflow-buffer
#20193
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Pull Request Overview
This PR fixes a false positive in the cpp/overflow-buffer query by properly handling reference types. The issue was that reference types were excluded from size calculations in one part of the getSize predicate but not in another, causing false positives when capturing destination variables by reference in lambdas.
- Extracts reference type handling into a shared helper predicate
getVariableSize - Updates both disjuncts of
getSizeto consistently exclude reference types from size calculations - Adds a test case demonstrating the fixed scenario with lambda capture by reference
Reviewed Changes
Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| Buffer.qll | Adds getVariableSize helper and updates getSize to consistently exclude reference types |
| tests.cpp | Adds test case test31 demonstrating lambda capture scenario that should not trigger false positive |
| UnboundedWrite.expected | Updates expected test results with corrected line numbers after adding new test case |
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We "handled" reference types in one disjunct of
getSize, but not in the other (where by "handle" I mean "excluded"). This caused some FPs when capturing the destination variable by reference in a lambda.This PR fixes that by properly excluding reference types as sources in both disjuncts.
Commit-by-commit review recommended.
DCA looks uneventful.