null pointers should not be dereferenced

SonarLint IntelliJ 4.0.0.2916 Java Rule 'Null pointers should not be dereferenced' I'm getting this fault in the next code when obj can't be null in any scenario. When B is null, The control reaches inside the main if block only when length of A is 1. Connect and share knowledge within a single location that is structured and easy to search. The 2nd NCCE/CS pair seems redundant with the first NCCE/CS pair. In some situations, however, dereferencing a null pointer can lead to the execution of arbitrary code [Jack 2007,van Sprundel 2006]. Hi @Michael! Search for vulnerabilities resulting from the violation of this rule on the CERT website. Making statements based on opinion; back them up with references or personal experience. The only potential null is the return value of list(). The correct idiom is to only allocate storage if the pointer is currently NULL. PS: I also tried the code in android studio which uses Lint and got no warnings. In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. How can this new ban on drag possibly be considered constitutional? At worst, it could expose debugging information that would be useful to an attacker, or When you have a variable of non-primitive type, it is a reference to an object. The 4gig boundary will probably be important too with unsigned int in LP64, but since size_t will be 64-bit, there will have to be some truncation that compilers will be able to warn on. Instead use String.valueOf (object). Software project. in above code, Passing ownership of something also requires pointers. }. This is a feature that we are currently heavily working on to be able to switch off such kind of false positives. Dereferencing > this null pointer may cause the kernel go wrong. Ticket opened : Thanks a lot for the minimalized reproducer ! ROSE does not handle cases where an allocation is assigned to an lvalue that is not a variable (such as a struct member or C++ function call returning a reference), Finds instances where a pointer is checked against NULL and then later dereferenced, Identifies functions that can return a null pointer but are not checked, Identifies code that dereferences a pointer and then checks the pointer against NULL, Can find the instances where NULL is explicitly dereferenced or a pointer is checked againstNULL but then dereferenced anyway. My question is; is my solution incorrect? Provide a self-contained reproducer (zipped project?) Doing so will at best cause abrupt program termination, without the I already tried to put ResponseEntity responseDto inside my try clause assigning and returning the respective value but its mandatory to return something out the try/catch. One could argue that all code examples would be redundant with the first pair. It is generally accepted that zeroing a pointer is a good way to mark it as invalid and dereferencing an invalid pointer is a bug. New replies are no longer allowed. SonarQube null pointers should not be dereferenced on try/catch, Sonarcube :Null pointers should not be dereferenced, How do you get out of a corner when plotting yourself into a corner. SonarQube Version 6.7.2 (build 37468) Solution 1, it looks like, today's solution tomorrow's problem. res.getBody() == null || res.getBody().getServiceResult() == null). Asking for help, clarification, or responding to other answers. sometimes FP occurs. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. You can use Optional instead. Also, the term 'pointer' is bad (but maybe it comes from the FindBugs tool): Java doesn't have pointers, it has references. SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, how to handle Sonarlint java:S2259 (Null pointers should not be dereferenced), How Intuit democratizes AI development across teams through reusability. A null pointer stores a defined value, but one that is defined by the environment to not be a valid address for any member or object. Because a null pointer does not point to a meaningful object, an attempt to dereference(i.e., access the data stored at that memory location) a null pointer usually (but not always) causes a run-time error or immediate program crash. Thanks for your relpy. So, this code should address the Sonar problem: You can also eliminate the null check using Optional>, like: Even I don't recommend this, you can just check the null responseDto without any use of Optional: Thanks for contributing an answer to Stack Overflow! With their flexibility, void pointers also bring some constraints. Interactions/interfaces with C can't use references. How to deal with "java.lang.OutOfMemoryError: Java heap space" error? But passing 0 to memcpy() is not one of them. At best, such an exception will cause abrupt program termination. In C, dereferencing a null pointer is undefined behavior. Powered by Discourse, best viewed with JavaScript enabled. Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? util.regex.Matcher, java - Swing .getParent() . The nature of simulating nature: A Q&A with IBM Quantum researcher Dr. Jamie We've added a "Necessary cookies only" option to the cookie consent popup. Basically, yes. All content is copyright protected. Explain about call by reference with an . But what exactly does it mean to "dereference a null pointer"? The value 0 for the number of bytes to copy is not what causes the UB, it's the null pointer value which triggers it. Because null pointer dereferencing is UB, the if (!tun) check can be elided entirely by the optimizer (since the tun->sk implies that tun must be non-null). The fact that you can't pass a null (no object) with a reference parameter can be a reason to use a pointer instead. Accessing or modifying a null object's field. Small typo nit: "such as if i t pointed to freed memory" meant to say "if it" instead (removing whitespace). String *x, y; X is a pointer to a string, Y is a string & = address of variable/ operator || referencing operator * = value of address || dereferencing operator Pointers = stores memory address as its variables NULL pointer = a constant with a value of zero defined || assigned to null Void pointer = a pointer that is not associated with any data types New operator = denotes a request for . The user_data pointer could be invalid in other ways, such as pointing to freed memory. The final NCCE is actually more insidious than it seems at first. Is it possible to rotate a window 90 degrees if it has the same length and width? Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. But even with this, the concerned object it tagged as a possible NullPointerException problem. What is a serialVersionUID and why should I use it? The nature of simulating nature: A Q&A with IBM Quantum researcher Dr. Jamie We've added a "Necessary cookies only" option to the cookie consent popup. The libpng library implements its own wrapper to malloc() that returns a null pointer on error or on being passed a 0-byte-length argument. In case the hash algorithm used for the signature is known to the OpenSSL library but the implementation of the hash algorithm is not available the digest initialization will fail. Agreed. (In contrast, the case of passing 0 bytes to malloc is addressed in C11.) The indicated severity is for this more severe case; on platforms where it is not possible to exploit a null pointer dereference to execute arbitrary code, the actual severity is low. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? HTTP request redirections should not be open to forging attacks Deserialization should not be vulnerable to injection attacks Endpoints should not be vulnerable to reflected cross-site scripting (XSS) attacks "CoSetProxyBlanket" and "CoInitializeSecurity" should not be used Database queries should not be vulnerable to injection attacks How to use java.net.URLConnection to fire and handle HTTP requests, Why should Java 8's Optional not be used in arguments, sonarLint complains "Null pointers should not be dereferenced (squid:S2259)" despite that possibility being handled. My below code where I'm calling a stored procedure is giving a null pointer exception. Should trycatch go inside or outside a loop? I think that checking for user_data being NULL would be an improvement to the CS so long as there is an explicit mention that user_data being NULL is invalid even if length == 0. I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. SonarJava. Essentially, this code and the previous dereference disagree as to whether this value is allowed to be null. I added a comment to explain that SIZE_MAX is the limit of size_t. How handle the initialization of "responseDto" without "null" because is throwing the issue on sonar. ncdu: What's going on with this second size column? There are many ways to resolve this. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Whoops, you're right. Are there tables of wastage rates for different fruit and veg? Dereferencing a null pointer is undefined behavior. This will normally lead to an unhandled error, resulting in a segmentation fault. A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. The nature of simulating nature: A Q&A with IBM Quantum researcher Dr. Jamie We've added a "Necessary cookies only" option to the cookie consent popup. What is the point of Thrower's Bandolier? Then we hit memcpy with length 0. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? assert(!invalid(p)); // or whatever, bool invalid(const void *p) { Reports. Find centralized, trusted content and collaborate around the technologies you use most. Batch split images vertically in half, sequentially numbering the output files, Difficulties with estimation of epsilon-delta limit proof, Minimising the environmental effects of my dyson brain. It also adds assertions to document that certain other pointers must not be null. MSBuild SonarQube Runner Resharper Plugin receives skipping info errors File not in sonarqube, SonarQube jenkins plugin returns "Server returned HTTP response code: -1, message: 'null' for URL: https://api.github.com/user", SonarQube: Ignore issues in blocks not working with regex, sonarLint complains "Null pointers should not be dereferenced (squid:S2259)" despite that possibility being handled, Java: (false?) Doing so will cause a NullPointerException to be thrown. The Clang Static Analyzer already has a checker to find the null pointer dereference in code, however it is not sufficient for higher abstractions such as C++ smart pointers or optionals. This is indeed an obvious False Positive from the rule. What is null pointer exception in android. I'd guess WG14 has considered these questions, but I haven't until now :). int changed to size_t and if size_t parameter's is zero, allocate one word. When I scan with sonar-lint in idea, it seams white list is useful, but when use sonar-scanner, always FP, org.springframework.util.CollectionUtils#isEmpty ucsi->connector gets dereferenced by both ucsi_connector_change() and ucsi_resume(), both check for ucsi->connector being NULL in case ucsi_init() has not finished yet; or in case ucsi_init() has failed. What are the effects of exceptions on performance in Java? Thanks for the feedback. In C# and Java, all reference types can point to null. Can I tell police to wait and call a lawyer when served with a search warrant? In the simplest case, this function just returns the result of calling kmalloc. Could I capture, and I would be able to glean much security information from the dump? Asking for help, clarification, or responding to other answers. Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, SonarQube - Null Pointer Dereference Issue.

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