CWE 401- Missing Release Of Memory After Effective Lifetime can occur when a program does not release memory after it is finished using it, that memory is said to be "leaked". A memory leak can occur when an allocated block of memory is no longer needed but the program fails to deallocate it. When this happens, the leaked memory continues to be used by the program and is not available for other processes. Over time, as more and more memory is leaked, the program will eventually crash.
Memory leaks can have a significant impact on the performance of a program. They can cause the program to use more memory than it needs, which can lead to excessive paging and decreased performance. In some cases, memory leaks can even cause the program to crash. To avoid memory leaks, programmers must be careful to always deallocate memory when it is no longer needed. In C and C++ programs, this can be accomplished using the free() function.
When a memory leak is discovered in a program, it is often possible to fix it by adding a call to free() at the appropriate point in the code. However, memory leaks can be difficult to track down, and in some cases it may not be possible to fix them without significant rewriting of the code.