CWE

Mismatched Memory Management Routines

ID: 762		Date: (C)2012-05-14   (M)2022-10-10
Type: weakness		Status: INCOMPLETE
Abstraction Type: Variant

Description

The application attempts to return a memory resource to the system, but it calls a release function that is not compatible with the function that was originally used to allocate that resource.

Extended Description

This weakness can be generally described as mismatching memory management routines, such as:

The memory was allocated on the stack (automatically), but it was deallocated using the memory management routine free() (CWE-590), which is intended for explicitly allocated heap memory.

The memory was allocated explicitly using one set of memory management functions, and deallocated using a different set. For example, memory might be allocated with malloc() in C++ instead of the new operator, and then deallocated with the delete operator.

When the memory management functions are mismatched, the consequences may be as severe as code execution, memory corruption, or program crash. Consequences and ease of exploit will vary depending on the implementation of the routines and the object being managed.

Likelihood of Exploit: Low

Applicable Platforms
Language: C
Language: C++
Language Class: Manual Memory Managed Languages

Time Of Introduction

• Implementation

Common Consequences

Scope	Technical Impact	Notes
Integrity Availability Confidentiality	Modify memory DoS: crash / exit / restart Execute unauthorized code or commands

Detection Methods
None

Potential Mitigations

Phase	Strategy	Description	Effectiveness	Notes
Implementation		Only call matching memory management functions. Do not mix and match routines. For example, when you allocate a buffer with malloc(), dispose of the original pointer with free().
Implementation	Libraries or Frameworks	To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.
Architecture and Design Implementation Operation	Libraries or Frameworks	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.

Relationships

Related CWE	Type	View	Chain
CWE-762 ChildOf CWE-891	Category	CWE-888

Demonstrative Examples   (Details)

1. This example allocates a BarObj object using the new operator in C++, however, the programmer then deallocates the object using free(), which may lead to unexpected behavior. (Demonstrative Example Id DX-80)

White Box Definitions
None

Black Box Definitions
None

Taxynomy Mappings

Taxynomy	Id	Name	Fit
CERT C++ Secure Coding	MEM39-CPP	Resources allocated by memory allocation functions must be released using the corresponding memory deallocation function

References:

1. .boost C++ Library Smart Pointers.
2. .Valgrind.