CWE-590: Free of Memory not on the Heap

Description:
The product calls free() on a pointer to memory that was not allocated using associated heap allocation functions such as malloc(), calloc(), or realloc().

Extended Description:
When free() is called on an invalid pointer, the program's memory management data structures may become corrupted. This corruption can cause the program to crash or, in some circumstances, an attacker may be able to cause free() to operate on controllable memory locations to modify critical program variables or execute code.

Affected languages: Memory-Unsafe, C
Parent weaknesses: CWE-762

Consequences:
  - Integrity: Execute Unauthorized Code or Commands

Detection methods:
  - Fuzzing: Fuzz testing (fuzzing) is a powerful technique for generating large numbers of diverse inputs - either randomly or algorithmically - and dynamically invoking the code with those inputs. Even with rand
  - Automated Static Analysis: Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without havin
  - Automated Dynamic Analysis: Use tools that are integrated during
	     compilation to insert runtime error-checking mechanisms
	     related to memory safety errors, such as AddressSanitizer
	     (ASan) for C/C++ [REF-1518] or 

Mitigations:
  - [Implementation] Only free pointers that you have called malloc on previously. This is the recommended solution. Keep track of which pointers point at the beginning of valid chunks and free them only once.
  - [Implementation] Before freeing a pointer, the programmer should make sure that the pointer was previously allocated on the heap and that the memory belongs to the programmer. Freeing an unallocated pointer will cause undefined behavior in the program.
  - [Architecture and Design] 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.

Demonstrative examples:
In this example, an array of record_t structs, bar, is allocated automatically on the stack as a local variable and the programmer attempts to call free() on the array. The consequences will vary based on the implementation of free(), but it will not succeed in deallocating the memory.
This example shows the array allocated globally, as part of the data segment of memory and the programmer attempts to call free() on the array.
void foo(){ 
                         record_t bar[MAX_SIZE]; 
                            
                            /* do something interesting with bar */ 
                            
                            ... free(bar); 
                      }
record_t bar[MAX_SIZE]; //Global var void foo(){ 
                         
                            
      

Real-world examples:
  - CVE-2023-22291: parser for a word processor attempts to free a stack pointer when intending to expand memory to hold a larger buffer