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 |
| MISRA2004-17_2 | Fully implementedCERT_C-ARR36-a CERT_C-ARR36-b | Do not subtract two pointers that do not address elements of the same array | |||||||||||||||||||
| R2017b | Subtraction or comparison between pointers to different arrays | Subtraction or comparison between pointers causes undefined behavior Subtraction between pointers shall only be applied to pointers that address elements of the same array | PRQA QA-C | ||||||||||||||||||||
| Include Page | PRQA QA-C_v | PRQA QA-C_v | 0487, 0513, 2771, 2772, | Fully implemented | PVS-Studio | ||||||||||||||||||
| Include Page | PVS-Studio_V | PVS-Studio_V | V736, V782
| 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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Taxonomy | Taxonomy item | Relationship |
|---|---|---|
| CERT C | CTR54-CPP. Do not subtract iterators that do not refer to the same container | Prior to 2018-01-12: CERT: Unspecified Relationship |
| ISO/IEC TS 17961 | Subtracting or comparing two pointers that do not refer to the same array [ptrobj] | Prior to 2018-01-12: CERT: Unspecified Relationship |
| CWE 2.11 | CWE-469, Use of Pointer Subtraction to Determine Size | 2017-07-10: CERT: Exact |
| CWE 3.11 | CWE-469, Use of Pointer Subtraction to Determine Size | 2018-10-18:CERT:CWE subset of rule |
CERT-CWE Mapping Notes
Key here for mapping notes
CWE-469 and ARR36-C
CWE-469 = Subset(ARR36-C)
ARR36-C = Union(CWE-469, list) where list =
- Pointer comparisons using the relational operators
<,<=,>=, and>, where the pointers do not refer to the same array
Bibliography
| [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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