When two pointers are subtracted, both must point to elements of the same array object or just one past the last element of the array object (C Standard, 6.5.6 7 [ISO/IEC 9899:20112024]); the result is the difference of the subscripts of the two array elements. Otherwise, the operation is undefined behavior. (See undefined behavior 48.)
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Tool | Version | Checker | Description | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Astrée |
| pointer-subtraction | Partially checked | ||||||
| Axivion Bauhaus Suite |
| CertC-ARR36 | Can detect operations on pointers that are unrelated | ||||||
| CodeSonar |
| LANG.STRUCT.CUP LANG.STRUCT.SUP | Comparison of Unrelated Pointers Subtraction of Unrelated Pointers | ||||||
| Coverity |
| MISRA C 2004 17.2 MISRA C 2004 17.3 MISRA C 2012 18.2 MISRA C 2012 18.3 | Implemented | ||||||
| Cppcheck |
| comparePointers | Fully implemented | ||||||
| Cppcheck Premium |
| comparePointers | Fully implemented | ||||||
| Helix QAC |
| C0487, C0513 DF2668, DF2669, DF2761, DF2762, DF2763, DF2766, DF2767, DF2768, DF2771, DF2772, DF2773 | |||||||
| Klocwork |
| MISRA.PTR.ARITH | |||||||
| LDRA tool suite |
| 437 S, 438 S | Fully implemented | ||||||
| Parasoft C/C++test |
| CERT_C-ARR36-a CERT_C-ARR36-b | Do not subtract two pointers that do not address elements of the same array | ||||||
| Checks for subtraction or comparison between pointers to different arrays (rule partially covered) | ||||||||
| PVS-Studio |
| V736, V782 | |||||||
| RuleChecker |
| pointer-subtraction | Partially checked | ||||||
| TrustInSoft Analyzer |
| differing_blocks | Exhaustively verified (see the compliant and the non-compliant example). |
Related Vulnerabilities
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
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| [Banahan 2003] | Section 5.3, "Pointers" Section 5.7, "Expressions Involving Pointers" |
| [ISO/IEC 9899:20112024] | 6.5.67, "Additive Operators" |
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