CWE Rule 766

This issue occurs when you declare a critical nonstatic data member of a class to be public. By default, Polyspace^® assumes that no data member is critical. Specify the critical data members in your code by using the code behavior CRITICAL_DATA. See Specifying Critical Data Members. If you do not specify any critical data members, Polyspace raises a warning during the analysis.

Declaring the critical data members as public allows the clients of a class to modify critical data members. You can inadvertently introduce vulnerabilities when critical data members are public. The vulnerabilities of such code are difficult to find and time-consuming to fix.

To fix this defect, determine which data members are critical and declare them as private or protected.

This defect checker requires a list of critical data members to be externally specified. Even if you enable checking of CWE rules, this checker is not enabled unless you also specify a list of critical data members. See Modify Bug Finder Checkers Through Code Behavior Specifications.

#include <string.h>
#define MAX_PASSWORD_LENGTH 15
#define MAX_USERNAME_LENGTH 15

class UserAccount
{
public:
  UserAccount(char *username, char *password)
  {
    //...
  }

  int authorizeAccess(char *username, char *password)
  {
    //...
  }

  char username[MAX_USERNAME_LENGTH+1];  //Noncompliant
  char password[MAX_PASSWORD_LENGTH+1];  //Noncompliant
};

In this example, the data members username and password are declared as public. Specify these variables as critical in a code behavior XML file:

<specifications>
   <members>
	<member name="password" kind="variable">
		<behavior name="CRITICAL_DATA"/>
	</member>
	<member name="username" kind="variable">
		<behavior name="CRITICAL_DATA"/>
	</member>
   </members>
</specifications>

To fix this defect, declare the critical variables as private

#include <string.h>


#define MAX_PASSWORD_LENGTH 15
#define MAX_USERNAME_LENGTH 15

class UserAccount
{
public:
  UserAccount(char *username, char *password)
  {
    //...
  }

  int authorizeAccess(char *username, char *password)
  {
    //...
  }
private:
  char username[MAX_USERNAME_LENGTH+1]; 
  char password[MAX_PASSWORD_LENGTH+1]; 
};