In this section:

Overview

This error is generated if the address of a global variable is passed to a routine that de-allocates memory.

Code	Description	Enabled	Reported	Platform
FREE_GLOBAL	Freeing global memory		Runtime	Windows/Unix

Problem

The following code attempts to deallocate a global variable that was not dynamically allocated.

/*
 * File: freeglob.c
 */
char a[10];

main()
{
	free(a);
	return (0);
}

Diagnosis at Runtime

[freeglob.c:8] **FREE_GLOBAL**
>>			 free(a);
Freeing global memory: a

---- Associated Common Weakness Enumerations ----
CWE-763: Release of invalid pointer or reference
CWE-590: Free of memory not on the heap

Pointer		 : 0x00012210
In block	 : 0x00012210 thru 0x00012217 (8 bytes)
					a,declared at freeglob.c, 4
Stack trace where the error occurred:
					main() freeglob.c, 8
**Memory corrupted. Program may crash!!**

• Line 2: Source line at which the problem was detected.
• Line 3: Description of the problem and the expression that is in error.
• Line 5-7: CWEs associated with this problem.
• Line 9: Value of the pointer that is being deallocated.
• Line 10: Information about the block of memory addressed by this pointer, including information about where this block was declared.
• Line 12: Stack trace showing the function call sequence leading to the error.
• Line 14: Informational message indicating that a serious error has occurred which may cause the program to crash.
  

Repair

Some systems allow this operation, since they keep track of which blocks of memory are actually dynamically allocated, but this is not portable programming practice and is not recommended.

In some cases, this error will result from a simple coding mistake at the indicated source line which can be quickly corrected.

A more complex problem may arise when a program uses both statically and dynamically allocated blocks in the same way. A common example is a linked list in which the head of the list is static, while the other entries are allocated dynamically. In this case, you must take care not to free the static list head when removing entries.

If your application is unable to distinguish between global and dynamically allocated memory blocks, you can suppress error messages by suppressing FREE_GLOBAL.

References

The table below shows Common Weakness Enumerations associated with this error.