The C Standard, Annex J (184) [ISO/IEC 9899:20112024], states that the behavior of a program is undefined when
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See also undefined behavior 179184.
Freeing memory that is not allocated dynamically can result in heap corruption and other serious errors. Do not call free() on a pointer other than one returned by a standard memory allocation function, such as malloc(), calloc(), realloc(), or aligned_alloc().
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The consequences of this error depend on the implementation, but they range from nothing to arbitrary code execution if that memory is reused by malloc().
Rule | Severity | Likelihood | Remediation Cost | Priority | Level |
|---|---|---|---|---|---|
MEM34-C | High | Likely | Medium | P18 | L1 |
Automated Detection
Tool | Version | Checker | Description | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Astrée |
| invalid-free | Fully checked | ||||||
| Axivion Bauhaus Suite |
| CertC-MEM34 | Can detect memory deallocations for stack objects | ||||||
| Clang |
| clang-analyzer-unix.Malloc | Checked by clang-tidy; can detect some instances of this rule, but does not detect all | ||||||
| CodeSonar |
| ALLOC. |
TM | Type Mismatch |
| Compass/ROSE |
Can detect some violations of this rule | |||||||||
| BAD_FREE | Identifies calls to | |||||||
| Cppcheck |
| autovarInvalidDeallocation mismatchAllocDealloc | Partially implemented | ||||||
| Cppcheck Premium |
| autovarInvalidDeallocation mismatchAllocDealloc | Partially implemented | ||||||
| Helix QAC |
| DF2721, DF2722, DF2723 | |||||||
| Klocwork |
| FNH.MIGHT FNH.MUST |
FUM.GEN.MUST
| LDRA tool suite |
| 407 S, 483 S, 644 S, 645 S, 125 D | Partially implemented | ||||||
| Parasoft C/C++test |
| CERT_C-MEM34-a | Do not free resources using invalid pointers |
| Parasoft Insure++ |
| Runtime analysis | |||||||||
| PC-lint Plus |
| 424, 673 | Fully supported | ||||||
| Polyspace Bug Finder |
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| Checks for:
|
Rule fully covered. | |||||||||
| PVS-Studio |
| V585, V726 | |||||||
| RuleChecker |
| invalid-free | Partially checked | ||||||
| TrustInSoft Analyzer |
| unclassified ("free expects a free-able address") | Exhaustively verified (see one compliant and one non-compliant example). |
Related Vulnerabilities
CVE-2015-0240 describes a vulnerability in which an uninitialized pointer is passed to TALLOC_FREE(), which is a Samba-specific memory deallocation macro that wraps the talloc_free() function. The implementation of talloc_free() would access the uninitialized pointer, resulting in a remote exploit.
Search for vulnerabilities resulting from the violation of this rule on the CERT website.
Related Guidelines
Key here (explains table format and definitions)
Taxonomy | Taxonomy item | Relationship |
|---|---|---|
| CERT C Secure Coding Standard | MEM31-C. Free dynamically allocated memory when no longer needed |
| Prior to 2018-01-12: CERT: Unspecified Relationship | ||
| CERT C | MEM51-CPP. Properly deallocate dynamically allocated resources | Prior to 2018-01-12: CERT: Unspecified Relationship |
| ISO/IEC TS 17961 | Reallocating or freeing memory that was not dynamically allocated [xfree] |
| Prior to 2018-01-12: CERT: Unspecified Relationship | ||
| CWE 2.11 | CWE-590, Free of Memory Not on the Heap | 2017-07-10: CERT: Exact |
Bibliography
| [ISO/IEC 9899: |
| 2024] | Subclause J.2, "Undefined Behavior" |
| [Seacord 2013b] | Chapter 4, "Dynamic Memory Management" |
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