static int cJSON_strcasecmp( const char *s1, const char *s2 )
{
	if ( ! s1 )
		return ( s1 == s2 ) ? 0 : 1;
	if ( ! s2 )
		return 1;
	for ( ; tolower(*s1) == tolower(*s2); ++s1, ++s2)
		if( *s1 == 0 )
			return 0;
	return tolower(*(const unsigned char *)s1) - tolower(*(const unsigned char *)s2);
}
The program copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow.