In this section:

Overview

This error is generated if the address of a local variable is passed to free.

Code	Description	Enabled	Reported	Platform
FREE_LOCAL	Freeing local memory		Runtime	Windows/Unix

Problem

The following code attempts to free a local variable that was not dynamically allocated.

/*
 * File: freelocl.c
 */
 main()
{
	char b, *a;

	a = &b;
	free(a);
	return (0);
}

Diagnosis at Runtime

[freelocl.c:9] **FREE_LOCAL**
>>			 free(a);
Freeing local memory: a

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

Pointer			 : 0xf7fffb0f
In block		 : 0xf7fffb0f thru 0xf7fffb0f (1 byte)
					b,declared at freelocl.c, 6
Stack trace where the error occurred:
			main() freelocl.c, 9
**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 most cases, this error will result from a simple coding mistake at the indicated source line which can be quickly corrected.

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

References

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