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Non-Compliant Code Example

In this non-compliant code example, the The first declaration of the identifier x is externally linked, while the second declaration is internally linked. Future use of this identifier results in undefined behavior.

int x; /* externally linked */

int main(void) {
   static int x; /* internally linked */
  ... /* use of identifier x results in undefined behavior */
}

Compliant Solution

In this compliant solution, more More descriptive identifier names are used, so as to avoid this problemavoiding any conflicts.

int external_x; /* externally linked */
int main(void) {
  static int internal_x; /* internally linked */
  .../* we're good to go */
}

Risk Assessment

Use of an identifier classified as both internally and externally linked causes undefined behavior in the program. However, it would be highly unlikely that an attacker could exploit this behavior to run arbitrary code.

Examples of vulnerabilities resulting from the violation of this rule can be found on the CERT website.

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