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.)
...
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, | C2668DF2669, | C2669DF2761, | C2761DF2762, | C2762DF2763, | C2763DF2766, | C2766DF2767, | C2767DF2768, | C2768DF2771, | C2771, C2772, C2773DF2772, 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) | PRQA QA-C | ||||||||||||||||
Include Page | PRQA QA-C_v | PRQA QA-C_v | 0487, 0513, 2668, 2669, 2761,||||||||||||||||
Fully implemented | 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.
...
[Banahan 2003] | Section 5.3, "Pointers" Section 5.7, "Expressions Involving Pointers" |
[ISO/IEC 9899:20112024] | 6.5.67, "Additive Operators" |
...