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Aaron:I suspect we are talking past each other. sonarqube . That interpretation of the standard is not supported universally. > Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to > the caller site. This will normally lead to an unhandled error, resulting in a segmentation fault. A reference to null should never be dereferenced/accessed. Java Specification Participation Agreement version in use: 2.0. It is useful to have a function with portable interface but platform-dependent implementation: extern bool invalid(const void *); How do you ensure that a red herring doesn't violate Chekhov's gun? Ticket opened : Thanks a lot for the minimalized reproducer ! But no where in that particular idiom would a NULL pointer necessarily be deferenced. The same problem we will have with "Add at least one assertion to this test case." isEmpty(Map map) Software Engineering Institute (I think you cover that in a different rule.) To learn more, see our tips on writing great answers. Which @NotNull Java annotation should I use? Void pointers cannot be dereferenced as any other pointer. Is there a solution to add special characters from software and how to do it, Acidity of alcohols and basicity of amines. What are the effects of exceptions on performance in Java? I'd guess null pointers are not valid, even though they point to 0 bytes. We can get a reference to point to null in the following ways: "uninitialized" reference type variables variables which are initialized with nulls and are assigned their real value afterward. Do not dereference null pointers Created by Jeffrey Gennari, last modified by Jill Britton on Jan 18, 2023 Dereferencing a null pointer is undefined behavior. Can you please start a new thread and be more explicit about the issue you are observing. Automated Detection Null pointer dereferences can happen in path-dependent ways. io.NotSerializableException : java. Provide a self-contained reproducer (zipped project?) Finally my method is returning a response with value of restTemplate. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. The issue is: memcpy() and friends do not explicitly state that a null pointer is a valid pointer value, even if the number of bytes to copy is 0. If copying takes place between objects that overlap, the behavior is undefined. 1 Answer Sorted by: 2 Your code needs to do something about the possible NullPointerException when some exception is caught, because in this scenario the responseDto will be null. Doing so will cause a NullReferenceException to be thrown. How to use Slater Type Orbitals as a basis functions in matrix method correctly? Asking for help, clarification, or responding to other answers. Then the reading of the buffer via bstr_printf() will then look at the pointer to process the final output. Connect and share knowledge within a single location that is structured and easy to search. The alert is related to the sonar rule : Null pointers should not be dereferenced. 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. This likely means that youre on an ancient version of the Java analyzer. And the compliant solution guarantees that the pointer will be valid if the code calls memcpy(). Making statements based on opinion; back them up with references or personal experience. What is a NullPointerException, and how do I fix it?,What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them? Is it possible to create a concave light? The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. 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. Share Improve this answer Follow answered Oct 5, 2017 at 16:27 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. (in the meantime, in case of any other false-positive suspicion, make sure to check those latest versions as bunch of improvements are regularly released). It could be non-null the first time but not the second time, sonar does not know this. It's still illegal. Off by one error: It is the third example. What does "Could not find or load main class" mean? What is a serialVersionUID and why should I use it? All rights are expressly reserved. Accessing or modifying a null object's field. Does a summoned creature play immediately after being summoned by a ready action? Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. A value is checked here to see whether it is null, but this value can't be null because it was previously dereferenced and if it were null a null pointer exception would have occurred at the earlier dereference. Im very new to sonar, is there a way to add methods to the whitelist? Find centralized, trusted content and collaborate around the technologies you use most. Why is there a voltage on my HDMI and coaxial cables? Write a semantic patch to nd cases where the result of calling kmalloc is dereferenced with no previous NULL pointer test. Software project. Connect and share knowledge within a single location that is structured and easy to search. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Goal Interactions/interfaces with C can't use references. The correct idiom is to only allocate storage if the pointer is currently NULL. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. You do not have permission to delete messages in this group, Either email addresses are anonymous for this group or you need the view member email addresses permission to view the original message. Avoid Returning null from Methods. Why are physically impossible and logically impossible concepts considered separate in terms of probability? As for copy vs pointer/reference - it depends. Phew, we're agreed here. In particular, ROSE ensures that any pointer returned by malloc(), calloc(), or realloc() is first checked for NULL before being used (otherwise, it is free()-ed). // <------- reported violation: NullPointerException might be thrown as 'bar' is nullable here, https://jira.sonarsource.com/browse/SONARJAVA-1490, https://groups.google.com/d/msgid/sonarqube/4752a999-246e-42c2-bbdc-8a44a5564ce9%40googlegroups.com. Basically, yes. If malloc() fails, it returns a null pointer that is assigned to c_str. Thanks for contributing an answer to Stack Overflow! in above code, The 2nd NCCE/CS pair seems redundant with the first NCCE/CS pair. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. If you preorder a special airline meal (e.g. C# static code analysis: Null pointers should not be dereferenced Products In-IDE IDE extension that lets you fix coding issues before they exist! that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. ), Does not guess that return values from malloc(), strchr(), etc., can be NULL (The return value from malloc() is NULL only if there is OOMo and the dev might not care to handle that. . 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. We can see that at obj.run(), obj can not be null, but is pointed out by Sonar. The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. Seems the analizer don't recognice the logic with the funcional object Optional. Small typo nit: "such as if i t pointed to freed memory" meant to say "if it" instead (removing whitespace). But when length of A is 1, the control never reaches the else block. This engine is validating execution paths and checking for non-null values or null-check along the way, exploring all the possibilities. We might set a pointer to null even if we are not freeing a object, simply to dissociate one object from another: tty_driver->tty = NULL; /* detach low level driver from the tty device */ The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. I feel my situation is not as complicated. Is there a proper earth ground point in this switch box? Not the answer you're looking for? 11 Sep, 2006. 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. 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. Appropriate typecasting is necessary. Currently I'm working with SonarQube solving issues but I'm facing a trouble to how handle null pointers that shouldn't be dereferenced. Finally, there is the matter of the compliant solution. We can not disable any rule, sonar do validation in "Sonar way" (actual name of profile :) ), so we will need to mark them "Wont fix" each time it appear again in new code. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. , NPE : null-, . These can be: Invoking a method from a null object. https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx Obviously the value of that pointer could have changed since the . How to deal with "java.lang.OutOfMemoryError: Java heap space" error? All content is copyright protected. 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. When I added the not null validation as sonar suggest. I guess you could write a proposal to modify the C Standard, but our coding standard is meant to provide guidance for the existing language. Should trycatch go inside or outside a loop? ii. 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(). That is only true if possibleNumbers contains no element.. BTW: none of these warnings are shown by . Is it possible to create a concave light? Just because something is a pointer does not mean you should call delete . My question is; is my solution incorrect? Put a new ResponseEntity is wrong because I won't know what will be the answer for the status of http. 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. 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. I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. (In contrast, the case of passing 0 bytes to malloc is addressed in C11.) In the meantime, Im locking this thread. In order to fix this, just do the following: BodyType body=res.getBody (); if (body == null || body.getServiceResult () == null) { return; } You can then even reuse body after that. which version of SonarQube are you using? How handle the initialization of "responseDto" without "null" because is throwing the issue on sonar. void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. Your code needs to do something about the possible NullPointerException when some exception is caught, because in this scenario the responseDto will be null. Essentially, this code and the previous dereference disagree as to whether this value is allowed to be null. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Sonar false-positive on rule: Null pointers should not be dereferenced, Null Pointer Dereference issue not detected when the pointer is returned by another function. Using Kolmogorov complexity to measure difficulty of problems? 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. 2008-2023 SonarSource S.A., Switzerland. uninitialized reference-type class members. Issues Components. The standard will simply copy 0 byteswhich is essentially a no-op. Cause we need throw our own Runtime Exception, well-known methods wont help. util.regex.Matcher, java - Swing .getParent() . A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. This compliant solution ensures that both input_str andthe pointer returned by malloc() are not null: This noncompliant code example is from a version of drivers/net/tun.c and affects Linux kernel 2.6.30 [Goodin 2009]: The sk pointer is initialized to tun->sk before checking if tun is a null pointer. sonarLint (3.2.) minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). Is null check needed before calling instanceof? To learn more, see our tips on writing great answers. Explain about call by reference with an . Thanks for the feedback. best, such an exception will cause abrupt program termination. 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. validated for null in your method declaration with it: 2008-2023 SonarSource S.A., Switzerland. Unless explicitly stated otherwise in the description of a particular function in this subclause, pointer arguments on such a call shall still have valid values, as described in 7.1.4. Is there a single-word adjective for "having exceptionally strong moral principles"? Powered by Discourse, best viewed with JavaScript enabled. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . A non-null but invalid pointer passed to memcpy() can indeed cause undefined behavior, but that is not the issue in the noncompliant codethe pointer will either be valid or null. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. Shouldn't the function check all pointers before dereferencing them or passing them to another function? to non-modifiable storage when the corresponding parameter is not const-qualified) or a type (after default argument promotion) not expected by a function with a variable number of arguments, the behavior is undefined. See the "Null pointer checks may be optimized away more aggressively" section inhttps://gcc.gnu.org/gcc-4.9/porting_to.htmlas an example with one common implementation. 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. @Tibor SonarQube version 5.6.6, IntelliJ SonarLint plugin 3.0.0.2041, Sonar: Null pointers should not be dereferenced, How Intuit democratizes AI development across teams through reusability. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. Making statements based on opinion; back them up with references or personal experience. The final NCCE is actually more insidious than it seems at first. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. C static code analysis: Null pointers should not be dereferenced C static code analysis Unique rules to find Bugs, Vulnerabilities, Security Hotspots, and Code Smells in your C code All rules 311 Vulnerability 13 Bug 74 Security Hotspot 18 Code Smell 206 Quick Fix 14 Tags "memset" should not be used to delete sensitive data Vulnerability It also uses the unsigned type size_t to pass the length parameter, ensuring that negative values are not passed to func(). A pointer is simply a variable that contains a memory address. When you have a variable of non-primitive type, it is a reference to an object. Identify where the allocation occurs. Believing that dereferencing NULL shouldn't crash the system doesn't make it true. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". Instead use String.valueOf (object). 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, 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! Trying to understand how to get this basic Fourier Series. Is the God of a monotheism necessarily omnipotent? Dereferencing > this null pointer may cause the kernel go wrong. This topic was automatically closed 7 days after the last reply. When and how should I use a ThreadLocal variable? 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. The method isNR(minRating) is a helper method that validate among other things, if the object minRating is null. If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. The n=0 is a mildly interesting edge case: Clearly a pointer that points to at least one valid byte could be used as the src or dest pointer to a call to memcpy(, 0). Dereferencing a null pointer can lead to a denial of service. Is there a single-word adjective for "having exceptionally strong moral principles"? A bug can cause them never to be reassigned. Passing a null pointer tomemcpy() would produce undefined behavior, even if the number of bytes to copy were 0. My below code where I'm calling a stored procedure is giving a null pointer exception. Im having trouble understanding your problem. Trying to understand how to get this basic Fourier Series. Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". In multithreaded programs, null pointer dereferences can violate cache coherency policies and can cause resource leaks. So no checking of the length is necessary (besides preventing integer overflow, which the compliant solution does). 1 Answer Sorted by: 1 Your code is ok. 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 After that, you call res.getBody() again. That makes sense. 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. NULL vs Uninitialized pointer - An uninitialized pointer stores an undefined value. Not the answer you're looking for? A pointer to null (the 0 memory address) should never be dereferenced/accessed. There is no guarantee that subsequent invocations are returning the same value, thats why issue is raised. By 'valid pointers' I mean that both src and dest pointers are not null and they both point to non-overlapping arrays containing at least n bytes each. This is a matter of style, and also following code walkthrough. 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. This is indeed an obvious False Positive from the rule. Is it possible to rotate a window 90 degrees if it has the same length and width? All rights are expressly reserved. So the SIZE_MAX check was unnecessary. That is why I explicitly check for this in my attempted solution. The null pointer check for writing or dereferencing should be a compiler flag or library setting. parsing /proc/self/maps under linux) one might find out whether the pointer points into mapped memory, but this is still not a guarantee of validity because it is very coarse-grained see again the above example. Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. context.RaiseException . Two null pointers will always be equal to each other. But when length of A is 1, the control never reaches the else block. 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. Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. rev2023.3.3.43278. Discover SonarLint SaaS Setup is effortless and analysis is automatic for most languages Discover SonarCloud Self-Hosted Fast, accurate analysis; enterprise scalability Discover SonarQube Secrets ABAP ncdu: What's going on with this second size column? But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. While the engine is in practice already able to explore code from other files if needed (relying solely on bytecode), we restrain this approach to a limited set of well-known methods from standard libraries, for which we know that behaviors are correctly produced. At best, such an exception will cause abrupt program termination. Is there a single-word adjective for "having exceptionally strong moral principles"? rev2023.3.3.43278. Pittsburgh, PA 15213-2612 What is pointed to should only be deleted if it was created with new. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? For example the following program doesn't compile. Connect and share knowledge within a single location that is structured and easy to search. The approximation of the try catch flow is such that we consider an exception can be thrown just after the curly brace of the try. () 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. If you write [ref], then a null pointer is not allowed, but if you write [unique], then a null pointer is permitted. If you try to access any member variables or methods with that variable, you are trying to dereference it. Asking for help, clarification, or responding to other answers. I've changed it to say null pointer instead of invalid pointer. There are many ways to resolve this. A reference to null should never be dereferenced/accessed. How can we prove that the supernatural or paranormal doesn't exist? static-code-analysis Unfortunately, its actual state also has some limitations, like the one you are hitting here. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? 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. But passing 0 to memcpy() is not one of them. A reference to Nothing should never be dereferenced/accessed. 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. 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?) 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" How can I check before my flight that the cloud separation requirements in VFR flight rules are met? SonarJava. If you call connect() function, it better do the connection, but failing simply because some ptr is NULL is not good behaviour -- failures should . To subscribe to this RSS feed, copy and paste this URL into your RSS reader. The result of calling such a helper function should be . The method isNR (minRating) is a helper method that validate among other things, if the object minRating is null public boolean isNR (AgencyRating rating) { return rating == null || isNR (rating.getRatgCaam ()); } When I added the not null validation as sonar suggest. How do I align things in the following tabular environment? Mutually exclusive execution using std::atomic? Software project. This noncompliant code example is derived from a real-world example taken from a vulnerable version of the libpng library as deployed on a popular ARM-based cell phone [Jack 2007]. Recovering from a blunder I made while emailing a professor. Can I tell police to wait and call a lawyer when served with a search warrant? return p == NULL || (char *)p < &_etext; It could be non-null the first time but not the second time, sonar does not know this. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? This code also violates ERR33-C. Detect and handle standard library errors. You need to benchmark. Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. Isn't easier just to check valid range of length? SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. A nonnegative return value represents the number of bytes successfully read (the return value is a "signed size" type, usually the native integer type for the target platform). Extended Description NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? I would also guess that pointers that point to the one-past-the-end of an array are also invalid. 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.