CWE-590 Variante Incomplet

Free of Memory not on the Heap

This vulnerability occurs when a program calls free() on a memory pointer that wasn't originally allocated using standard heap functions like malloc(), calloc(), or realloc().

Définition

What is CWE-590?

This vulnerability occurs when a program calls free() on a memory pointer that wasn't originally allocated using standard heap functions like malloc(), calloc(), or realloc().
Calling free() on an invalid pointer corrupts the program's internal memory management structures. This corruption typically leads to a crash, but it can also create opportunities for an attacker to manipulate the memory process. In some cases, an attacker can steer the free() operation to target controllable memory locations, potentially altering critical variables or even executing malicious code. Detecting these 'invalid free' issues manually is challenging, as they often involve complex pointer tracking across codebases. While SAST tools can flag the pattern, Plexicus uses AI to analyze the data flow and suggest precise code fixes, transforming a tedious security hunt into an automated remediation step and saving significant developer time.
Impact réel

Real-world CVEs caused by CWE-590

Aucune référence CVE publique n'est liée à ce CWE dans le catalogue MITRE pour le moment.

Comment les attaquants l'exploitent

Parcours de l'attaquant étape par étape

  1. 1

    In this example, an array of record_t structs, bar, is allocated automatically on the stack as a local variable and the programmer attempts to call free() on the array. The consequences will vary based on the implementation of free(), but it will not succeed in deallocating the memory.

  2. 2

    This example shows the array allocated globally, as part of the data segment of memory and the programmer attempts to call free() on the array.

  3. 3

    Instead, if the programmer wanted to dynamically manage the memory, malloc() or calloc() should have been used.

  4. 4

    Additionally, global variables could be passed to free() when they are pointers to dynamically allocated memory.

Exemple de code vulnérable

Vulnerable C

In this example, an array of record_t structs, bar, is allocated automatically on the stack as a local variable and the programmer attempts to call free() on the array. The consequences will vary based on the implementation of free(), but it will not succeed in deallocating the memory.

Vulnérable C 
void foo(){
  		record_t bar[MAX_SIZE];
```
/* do something interesting with bar */* 
  		
  		...
  		free(bar);}
Exemple de code sécurisé

Secure C

Instead, if the programmer wanted to dynamically manage the memory, malloc() or calloc() should have been used.

Sécurisé C 
void foo(){
  		record_t *bar = (record_t*)malloc(MAX_SIZE*sizeof(record_t));
```
/* do something interesting with bar */* 
  		
  		...
  		free(bar);}
What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Liste de contrôle de prévention

How to prevent CWE-590

  • Implementation Only free pointers that you have called malloc on previously. This is the recommended solution. Keep track of which pointers point at the beginning of valid chunks and free them only once.
  • Implementation Before freeing a pointer, the programmer should make sure that the pointer was previously allocated on the heap and that the memory belongs to the programmer. Freeing an unallocated pointer will cause undefined behavior in the program.
  • Architecture and Design Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, glibc in Linux provides protection against free of invalid pointers.
  • Architecture and Design Use a language that provides abstractions for memory allocation and deallocation.
  • Testing Use a tool that dynamically detects memory management problems, such as valgrind.
Signaux de détection

How to detect CWE-590

Fuzzing High

Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with random inputs, it is often capable of generating unexpected results such as crashes, memory corruption, or resource consumption. Fuzzing effectively produces repeatable test cases that clearly indicate bugs, which helps developers to diagnose the issues.

Automated Static Analysis High

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

Correction automatique Plexicus

Plexicus détecte automatiquement CWE-590 et ouvre une PR de correction en moins de 60 secondes.

Codex Remedium analyse chaque commit, identifie cette faiblesse précise et livre une pull request prête à être relue avec le correctif. Pas de tickets. Pas de transferts.

Obtenir une démo Essayer Plexicus gratuitement
Questions fréquentes

Frequently asked questions

Qu'est-ce que CWE-590 ?

This vulnerability occurs when a program calls free() on a memory pointer that wasn't originally allocated using standard heap functions like malloc(), calloc(), or realloc().

Quelle est la gravité de CWE-590 ?

MITRE n'a pas publié de note de probabilité d'exploitation pour cette faiblesse. Traitez-la comme un impact moyen jusqu'à ce que votre modèle de menace prouve le contraire.

Quels langages ou plateformes sont affectés par CWE-590 ?

MITRE n'a pas spécifié les plateformes affectées pour ce CWE — il peut s'appliquer à la plupart des stacks applicatives.

Comment puis-je prévenir CWE-590 ?

Only free pointers that you have called malloc on previously. This is the recommended solution. Keep track of which pointers point at the beginning of valid chunks and free them only once. Before freeing a pointer, the programmer should make sure that the pointer was previously allocated on the heap and that the memory belongs to the programmer. Freeing an unallocated pointer will cause undefined behavior in the program.

Comment Plexicus détecte et corrige CWE-590 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-590 à chaque commit. Lorsqu'une correspondance est trouvée, notre agent Codex Remedium ouvre une PR de correction avec le code corrigé, les tests et un résumé d'une ligne pour le relecteur.

Où puis-je en savoir plus sur CWE-590 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/590.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-590

CWE-762 Parent

Mismatched Memory Management Routines

This vulnerability occurs when a program uses incompatible functions to allocate and free memory. For example, freeing memory with a…

CWE-123 Peut précéder

Write-what-where Condition

A write-what-where condition occurs when an attacker can control both the data written and the exact memory location where it's written,…

Ressources

Further reading

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