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.
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.
(Bad Code)
Example
Language: C++
void foo(){
BarObj *ptr = new BarObj()
/* do some work with ptr here */
...
free(ptr);
}
Instead, the programmer should have either created the object with one
of the malloc family functions, or else deleted the object with the
delete operator.
(Good Code)
Example
Language: C++
void foo(){
BarObj *ptr = new BarObj()
/* do some work with ptr here */
...
delete ptr;
}
Potential Mitigations
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
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.
Phases: Architecture and Design; Implementation; Operation
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.
Description
