Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. What is a serialVersionUID and why should I use it? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, It is a false positive, but it might be a good idea not to do the, Sonar false-positive on rule: Null pointers should not be dereferenced, How Intuit democratizes AI development across teams through reusability. I've changed it to say null pointer instead of invalid pointer. Find centralized, trusted content and collaborate around the technologies you use most. 11 Sep, 2006. Whats the grammar of "For those whose stories they are"? Reports. That is only true if possibleNumbers contains no element.. BTW: none of these warnings are shown by . I reordered that code example to do all the checks before allocations. The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. Making statements based on opinion; back them up with references or personal experience. Thanks for contributing an answer to Stack Overflow! It does not point to any area of memory. (In contrast, the case of passing 0 bytes to malloc is addressed in C11.) That makes sense. My main problem is because I'm doing a restTemplate.exchange with try-catch and declaring a variable with null value before the clause try and then using it inside the try. The above check can't hurt, as I guess you could have a system with a 32-bit size_t that had a ton of memory and had some crazy banking/selector scheme with pointers. 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. There are many ways to resolve this. Shouldn't the function check all pointers before dereferencing them or passing them to another function? This sounds indeed like a bug in the flow when an exception is raised. SIZE_MAX is the largest possible value that a size_t could take, so it is not possible to have anything larger than SIZE_MAX. Powered by Discourse, best viewed with JavaScript enabled. Then we hit memcpy with length 0. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. We really appreciate your help. . which version of SonarQube are you using? At Provide a self-contained reproducer (zipped project?) Are there tables of wastage rates for different fruit and veg? That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. ", Eclipse - Sonar S2629 possible false positive with new String, SonarQube null pointers should not be dereferenced on try/catch, getTextContent() through "Null pointers should not be dereferenced". What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. On such a call, a function that locates a character finds no occurrence, a function that compares two character sequences returns zero, and a function that copies characters copies zero characters. 3.7. In the code, we check the not nullity with java.util.Objects.nonNull(). Software Engineering Institute Solution 1, it looks like, today's solution tomorrow's problem. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. A reference to Nothing should never be dereferenced/accessed. You need to benchmark. Thank you for clarifying your assertion until I understood it properly. I would also guess that pointers that point to the one-past-the-end of an array are also invalid. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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 In the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. 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. Which ensures that the chunkdata pointer is valid, but makes no such check to the user_data pointer. To learn more, see our tips on writing great answers. NullPointerException is thrown when program attempts to use an object reference that has the null value. Share Improve this answer Follow answered Oct 5, 2017 at 16:27 The only potential null is the return value of list(). 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. All rights are expressly reserved. Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. The method isNR(minRating) is a helper method that validate among other things, if the object minRating is null. Is null check needed before calling instanceof? The chunkdata pointer is later used as a destination argument in a call to memcpy(), resulting in user-defined data overwriting memory starting at address 0. If you try to access any member variables or methods with that variable, you are trying to dereference it. I would therefore assert that a platform whose memcpy() did anything besides a no-op when given n=0 and valid source/destination pointers was not C-standards-compliant. Obviously the value of that pointer could have changed since the . 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} ncdu: What's going on with this second size column? SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. null(java.lang.NullPointerException) . In my experience, there are reasons to check for a NULL pointer other than dereferencing it. This rule applies to all null pointers, regardless of which function returned them. Connect and share knowledge within a single location that is structured and easy to search. How to use Slater Type Orbitals as a basis functions in matrix method correctly? Unfortunately, its actual state also has some limitations, like the one you are hitting here. NULL vs Uninitialized pointer - An uninitialized pointer stores an undefined value. 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. In the case of the ARM and XScale architectures, the 0x0 address is mapped in memory and serves as the exception vector table; consequently, dereferencing 0x0 did not cause an abnormal program termination. Goal Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Why does Mister Mxyzptlk need to have a weakness in the comics? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. What does it mean that a reference must refer to an object, not a dereferenced null pointer? which would allow us to systematically observe what you are having. 4. NULL vs Void Pointer - Null pointer is a value, while void pointer is a type. Doing so will cause a NullPointerException to be thrown. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. On the command prompt, the same arguments work and the record is added in db but not when I call the stored procedure from inside java program CallableStatement insertStat = db_conn.prepareCall (" {call InsertCourses (?,?,?,?,?,?,?,? Making statements based on opinion; back them up with references or personal experience. This issues is displayed by SonarQube. Connect and share knowledge within a single location that is structured and easy to search. Is it possible to rotate a window 90 degrees if it has the same length and width? Java Specification Participation Agreement version in use: 2.0. Find centralized, trusted content and collaborate around the technologies you use most. 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! We. Also, the term 'pointer' is bad (but maybe it comes from the FindBugs tool): Java doesn't have pointers, it has references. Is there a single-word adjective for "having exceptionally strong moral principles"? Why do academics stay as adjuncts for years rather than move around? You can use Optional instead. And the semantics, as I said, are different. Is there a solution to add special characters from software and how to do it, Acidity of alcohols and basicity of amines. At worst, it could expose debugging information that would be useful to an attacker or it could allow an Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? - the incident has nothing to do with me; can I use this this way? The expected result here is solve the issue with sonarqube. My below code where I'm calling a stored procedure is giving a null pointer exception. False-positives are pointed out in other SO posts (1 & 2), where nulls are involved across functions and procedures. When B is null, The control reaches inside the main if block only when length of A is 1. Im very new to sonar, is there a way to add methods to the whitelist? Is the God of a monotheism necessarily omnipotent? 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. What is the point of Thrower's Bandolier? This compliant solution ensures that the pointer returned by png_malloc() is not null. My question is; is my solution incorrect? Doing so will cause a NullReferenceException to be thrown. Extended Description NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions. I was fixing some issues gathered by SonarQube when I stumbled upon the following issue: SonarQube violation: Possible null pointer dereference in ___ due to return value of called method, This error was found in the following code: else if (foo.list().length > 0) { }, I attempted to resolve this by rewriting as: else if (null != foo.list() && foo.list().length > 0) { }, foo is an instance of the File class in Java, and is directly instantiated through new File(). Cause we need throw our own Runtime Exception, well-known methods wont help. JCP version in use: 2.6. Interactions/interfaces with C can't use references. https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. The alert is related to the sonar rule : Null pointers should not be dereferenced. Could I capture, and I would be able to glean much security information from the dump? Revert Update S2259: "Null pointer dereference" CFG should ignore expressions in Debug.Assert #397 Introduce means to not raise "Expression always true/false" on values that were checked with Debug.Assert. Explain about call by reference with an . name result . By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. IDE extension that lets you fix coding issues before they exist! How to deal with "java.lang.OutOfMemoryError: Java heap space" error? Basically, yes. Asking for help, clarification, or responding to other answers. Batch split images vertically in half, sequentially numbering the output files, Recovering from a blunder I made while emailing a professor. Why does the second compliant example permit using possibly-null pointers?