Mismatched Memory Management Routines
Mismatched Memory Management Routines
CWE-762
Short description
Extended description
This weakness can be generally described as mismatching memory management routines, such as:
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.
- 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.
Best practices to prevent this CWE
Phase: 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().
Phase: Implementation
Strategy: Libraries or Frameworks
Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
For example, glibc in Linux provides protection against free of invalid pointers.
When using Xcode to target OS X or iOS, enable automatic reference counting (ARC).
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.
Phase: Architecture and Design
Strategy: 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.
Phase: Architecture and Design
Use a language that provides abstractions for memory allocation and deallocation.
Phase: Testing
Use a tool that dynamically detects memory management problems, such as valgrind.
