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:
1. 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.
2. 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.
Time of Introduction
Implementation
Demonstrative Examples
Example 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.
(Bad Code)
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)
C++
void foo(){
BarObj *ptr = new BarObj()
/* do some work with ptr here */
...
delete ptr;
}
Potential Mitigations
Phase
Description
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
When programming in C++, consider using smart pointers provided by the
boost library to help correctly and consistently manage memory.
Implementation
Operation
Use a library that contains built-in protection against free of
invalid pointers, such as glibc.
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.
Description
