1. Vulnerability Description

• If you use the closed file pointer, you can perform an unintended action.

2. Vulnerability Countermeasure

• Do not use closed file pointer

3. Sample Code

• Vulnerable Code

#include <stdio.h>
int main( )
{
	FILE *pFile = NULL;
	pFile = fopen( "text.txt", "w+t" );
	if( pFile != NULL ) {
		fputs( "test1", pFile );
		fclose( pFile );
	} 
        ...
        fputs( "test2", pFile );
	return 0;
}

• Safe Code

#include <stdio.h>
int main( )
{
	FILE *pFile = NULL;
	pFile = fopen( "text.txt", "w+t" );
	if( pFile != NULL ) {
		fputs( "test1", pFile );
		fclose( pFile );
		pFile = NULL;
	} 
        ...
	return 0;
}