Dated: 04-12-2024

Ch03. case Study Security Hardening - C Applications

• Carnegie Mellon Software Engineering Institute
• https://wiki.sei.cmu.edu/confluence/display/seccode/SEI+CERT+Coding+Standards
• https://wiki.sei.cmu.edu/confluence/display/c/SEI+CERT+C+Coding+Standard
  
• There are existing compiler implementations that allow const-qualified objects to be modified without generating a warning message.
• Avoid casting away const qualification because doing so makes it possible to modify const-qualified objects without issuing diagnostics.

const int **ipp;
int *ip;
const int i = 42;

void func(void) {
    ipp = &ip; // Constraint Violation
    *ipp = &i; // Valid
    *ip = 0    // Modifies constant i (was 42)
}

• The first assignment is unsafe because it allows the code that follows it to attempt to change the value of the const object i.

int **ipp;
int *ip;
int i = 42;

void func(void) {
    ipp = &ip; // valid 
    *ipp = &i; // valid 
    *ip = 0    // valid 
}

• The compliant solution depends on the intent of the programmer. If the intent is that the value of i is modifiable, then it should not be declared as a constant, as in this compliant solution:
• If the intent is that the value of i is not meant to change, then do not write noncompliant code that attempts to modify it.
• Risk Assessment
• Automated detection
• Related vulnerabilities