Difference between revisions of "Omitted break statement"

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(Examples)
Line 49: Line 49:
 
Java:
 
Java:
  
 +
<pre>
 
{     
 
{     
 
     int month = 8;
 
     int month = 8;
Line 67: Line 68:
 
         println(" is a great month");
 
         println(" is a great month");
 
   }
 
   }
 +
</pre>
  
 
C/C++:  
 
C/C++:  
Line 72: Line 74:
 
Is identical if one replaces print with printf or cout.
 
Is identical if one replaces print with printf or cout.
  
Now one might think that if they just tested case12, it will display that the respective month "is a great month." However, if one tested November, one notice that it would display "November December is a great month."
+
One might think that if they just tested case12, it will display that the respective month "is a great month." However, if one tested November, one notice that it would display "November December is a great month."
  
 
==Related problems ==
 
==Related problems ==

Revision as of 12:03, 16 April 2006



Overview

Omitting a break statement so that one may fall through is often indistinguishable from an error, and therefore should not be used.

Consequences

Unspecified.

Exposure period

  • Pre-design through Build: The use of tools to detect this problem is recommended.
  • Implementation: Many logic errors can lead to this condition. It can be exacerbated by lack of or misuse of mitigating technologies

Platform

  • Languages: C/C++/Java
  • Operating platforms: Any

Required resources

Any

Severity

High

Likelihood of exploit

Medium

Avoidance and mitigation

  • Pre-design through Build: Most static analysis programs should be able to catch these errors.
  • Implementation: The functionality of omitting a break statement could be clarified with an if statement. This method is much safer.

Discussion

While most languages with similar constructs automatically run only a single branch, C and C++ are different. This has bitten many programmers, and can lead to critical code executing in situations where it should not.

Examples

Java:

{    
    int month = 8;
        switch (month) {
            case 1:  print("January");
            case 2:  print("February");
            case 3:  print("March");
            case 4:  print("April");
            case 5:  println("May");
            case 6:  print("June");
            case 7:  print("July");
            case 8:  print("August");
            case 9:  print("September");
            case 10: print("October");
            case 11: print("November");
            case 12: print("December");
        }
        println(" is a great month");
  }

C/C++:

Is identical if one replaces print with printf or cout.

One might think that if they just tested case12, it will display that the respective month "is a great month." However, if one tested November, one notice that it would display "November December is a great month."

Related problems

Not available.

Categories