All other exceptions are permitted to propagate to the next catch clause of a try statement on the stack. ERRJ-EX0: A catch block may catch all exceptions to process them before rethrowing them filtering sensitive information from exceptions before the call stack leaves a trust boundary, for example. Refer to ERRJ. In such cases, a catch block should catch Throwable rather than Exception or RuntimeException.
This code sample catches all exceptions and wraps them in a custom DoSomethingException before rethrowing them:. Exception wrapping is a common technique to safely handle unknown exceptions. For another example, see ERRJ. Do not throw undeclared checked exceptions. ERRJ-EX1: Task processing threads such as worker threads in a thread pool or the Swing event dispatch thread are permitted to catch RuntimeException when they call untrusted code through an abstraction such as the Runnable interface [ Goetz , p.
ERRJ-EX2: Systems that require substantial fault tolerance or graceful degradation are permitted to catch and log general exceptions such as Throwable at appropriate levels of abstraction. For example:. Catching NullPointerException may mask an underlying null dereference, degrade application performance, and result in code that is hard to understand and maintain.
Likewise, catching RuntimeException , Exception , or Throwable may unintentionally trap other exception types and prevent them from being handled properly. Throwable and Error should not be caught. I came across this CWE entry which uses a Java example and says precisely -. The default error page of a web application should not display sensitive information about the software system.
A Web application must define a default error page for 4xx errors e. Throwable exceptions to prevent attackers from mining information from the application container's built-in error response. In the snippet below, an unchecked runtime exception thrown from within the try block may cause the container to display its default error page which may contain a full stack trace, among other things. By catching Throwable they address one problem but violate this rule. Do not allow exceptions to transmit sensitive information a recommendation and not a rule?
It has all the hallmarks of a solid rule to me. Thanks Dave. Regarding EXCJ, the kind of sensitive information revealed through exceptions by itself does not always cause a vulnerability. That's why it's a recommendation. If it becomes a rule then there would be questions on what exactly constitutes "sensitive information". Unless that whole gap of determining what all "sensitive" includes is filled which would be a good exercise actually , we could keep it the way it is.
What information is considered 'sensitive' is defined by your security policy. For instance, if the user already has access to the file system, then information such as file system structre is not 'sensitive', and exceptions like FileNotFoundException require no filtering.
I still say that EXCJ should be a rule not a rec, as sensitive info disclosure is a security vulnerability by definition. Let the policymakers decide what constitutes 'sensitive' The intro might need to reflect that. Similarly the EXCJ. Try to gracefully recover from system errors could catch StackOverflowError and then Throwable. It seems it would actually violate the rule. This rule tells you to catch specific exceptions but not a generic type like RuntimeException, even if its catch block occurs after the specific exception is caught.
Bottom line, this code does violate the rule unless it is part of a top-level routine to protect the user from 'unknown' exceptions. I suggest changing the CE to:. In the 2nd CE, the none of the expressions in the divide method throw IOException , which makes the method declaration a bit confusing.
Maybe an comment alluding to some doing some other things that could cause IOException to be thrown would be worthwhile. If the first CS is changed, then it will become harder to explain the point of this guideline i. Let's just say that this code falls under the exception to EXCJ and is consequently, valid. This would not violate any secure coding rules.
It might be unusual to check if an illegal array access is made as opposed to checking for null but that doesn't mean it is an exemplar. A good question to ask is - why does jdk source code catch unchecked exceptions? Need an exception to catch generalized exceptions if working with a library that throws generalized exceptions. Even though that is a violation of EXCJ. Exception added. Do we now have a reasonable set of exceptions listed?
Doesn't this violate EXPJ. Never dereference null pointers? Shouldn't the parameter explicitely checked? In that case the NullPointerException has to be explicitly thrown. At least I would prefer that, because:. Are there any other differences between explicitely throwing the NullPointerException or let the JVM do it implicitely, like performance disadvantages?
Never dereference null pointers rather than with this rule, so I've addressed it there. I wrote an article about how to avoid NullPointerException.
First we need to do a null check on the map object itself. If this is not done, and the map is null , then a NullPointerException is thrown. This is done using testMap! Once that is done, check if a particular key is present before accessing it. You can check the presence of the key using testMap. If this is not done and the particular key is absent, then you will get the value as null. If you know for certain that a particular variable can never be null , then you can avoid adding the null check.
This maybe applicable in private functions where you can control the data going into function. But if you are not really certain about the nullability of an object, it is best to add a null check. All the code discussed in this article can be found in this Github repo. I love technology and follow advancements in the field. I also like helping others with my knowledge of tech. Feel free to read more of my articles on my blog , connect with me on LinkedIn , or follow me on Twitter.
If you read this far, tweet to the author to show them you care. Tweet a thanks. Learn to code for free. Instead of invoking the method from the null object, consider invoking it from the literal.
Otherwise, it will throw an IllegalArgumentException and notify the calling method that something is wrong with the passed arguments. First, the Boolean expression is evaluated. If the expression is true then, the value1 is returned, otherwise, the value2 is returned. Otherwise, if str point to actual data , the message will retrieve the first 6 characters of it as in case 2.
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