null pointers should not be dereferenced

Check whether a String is not Null and not Empty. Is there a single-word adjective for "having exceptionally strong moral principles"? This is a matter of style, and also following code walkthrough. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). 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. Much like dereferencing a dangling (or wild) pointer leads to undefined behavior, dereferencing a null pointer also leads to undefined behavior. Put a new ResponseEntity is wrong because I won't know what will be the answer for the status of http. - the incident has nothing to do with me; can I use this this way? Mutually exclusive execution using std::atomic? The solution that I recommend is not work with null returns or variables on Java, try to avoid it. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. So let me be more precise in my wording: I assert that a platform whose memcpy() did anything besides copy zero bytes when given n=0 and valid src and dest pointers was not C-standards-compliant. isEmpty(Map map) What is pointed to should only be deleted if it was created with new. Asking for help, clarification, or responding to other answers. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Null pointer should not be dereferenced , In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. I think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. Description: This JSR will work to develop standard annotations (such as @NonNull) that can be applied to Java programs to assist tools that detect software defects. Asking for help, clarification, or responding to other answers. In the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). NULL vs Void Pointer - Null pointer is a value, while void pointer is a type. 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. 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 multithreaded programs, null pointer dereferences can violate cache coherency policies and can cause resource leaks. One could argue that all code examples would be redundant with the first pair. Doing so will cause a NullPointerException to be thrown. Pointer members in structs are not checked. At best, such an exception will cause abrupt program termination. Thanks for contributing an answer to Stack Overflow! 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. The method isNR(minRating) is a helper method that validate among other things, if the object minRating is null. The same problem we will have with "Add at least one assertion to this test case." sonar-java. Replacing broken pins/legs on a DIP IC package, Bulk update symbol size units from mm to map units in rule-based symbology, How do you get out of a corner when plotting yourself into a corner. 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. IMHO, the rule title should be changed to something less general. Whoops, you're right. ssize_t (*aio_read)(struct kiocb *, char __user *, size_t . 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. Java Specification Participation Agreement version in use: 2.0. Is the God of a monotheism necessarily omnipotent? If you write [ref], then a null pointer is not allowed, but if you write [unique], then a null pointer is permitted. I have checked on multiple . Doing so will cause a NullReferenceException to be thrown. 2008-2023 SonarSource S.A., Switzerland. "After the incident", I started to be more careful not to trip over things. My below code where I'm calling a stored procedure is giving a null pointer exception. Here is our source code: Sign in to download full-size image Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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 . If you try to access any member variables or methods with that variable, you are trying to dereference it. NULL vs Uninitialized pointer - An uninitialized pointer stores an undefined value. Many platforms can support testing for those also. 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 What sort of strategies would a medieval military use against a fantasy giant? Your code needs to do something about the possible NullPointerException when some exception is caught, because in this scenario the responseDto will be null. How can we prove that the supernatural or paranormal doesn't exist? 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. What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. Pittsburgh, PA 15213-2612 Software Engineering Institute Explain about call by reference with an . Is there a single-word adjective for "having exceptionally strong moral principles"? ncdu: What's going on with this second size column? Dereferencing a null pointer results in undefined behavior. A pointer to null (the 0 memory address) should never be dereferenced/accessed. In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. There is no legitimate reason to dereference a null pointer unless you on a rare system that maps page zero (or you intend your program to crash). Finally, there is the matter of the compliant solution. Why do academics stay as adjuncts for years rather than move around? ", 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". Possible fix: Assign a valid address to the pointer in all branches of the conditional statement.. Pointer can point to dynamically allocated memory. For the time being, I would unfortunately recommend to mark as False Positive the issue. Goal 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" [4] 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. It's a modular system with the . rev2023.3.3.43278. As a result, this noncompliant code example is vulnerable to a null pointer dereference exploit, because null pointer dereferencing can be permitted on several platforms, for example, by using mmap(2) with the MAP_FIXED flag on Linux and Mac OS X, or by using the shmat() POSIX function with the SHM_RND flag [Liu 2009]. I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). This latter use of pointers is a combined boolean/satellite: the pointer being non-null indicates "I have this sister object", and it provides that object. I feel my situation is not as complicated. 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. 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. java There are many ways to resolve this. Trying to understand how to get this basic Fourier Series. Im very new to sonar, is there a way to add methods to the whitelist? What is a NullPointerException, and how do I fix it?,What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them? To create a custom null validation method declare an attribute with name ValidatedNotNullAttribute and mark the parameter that is Phew, we're agreed here. We have a false positive with the " Null pointers should not be dereferenced -squid:S2259" rule : We have a "NullPointerException" false positive for which we do not know how to solve it. I have a sonar alert on this call minRating.getRatgCaam(). Is it possible to rotate a window 90 degrees if it has the same length and width? Made code more compliant with other rules. There is a missing check for the return value from . A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. It also uses the unsigned type size_t to pass the length parameter, ensuring that negative values are not passed to func(). 0 is certainly within the 'domain of the function' (a phrase defined by mathematics but not by C11), as copying 0 bytes is well-understood (although silly). But when length of A is 1, the control never reaches the else block. Which version of SonarJava plugin do you have? If you preorder a special airline meal (e.g. Please explain: Without this, we wont be able to help you. (I think you cover that in a different rule.) The null pointer check for writing or dereferencing should be a compiler flag or library setting. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. I'd guess WG14 has considered these questions, but I haven't until now :). 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. {"serverDuration": 214, "requestCorrelationId": "084acdc104f21c51"}, EXP34-C. Do not dereference null pointers, Clever Attack Exploits Fully-Patched Linux Kernel, ERR33-C. Detect and handle standard library errors, one compliant and one non-compliant example, CERT Oracle Secure Coding Standard for Java, EXP01-J. Is a PhD visitor considered as a visiting scholar? To learn more, see our tips on writing great answers. And fwstr > is dereferenced in the following codes. It also reinforces the notion to the reader that any time you see arithmetic in an allocation expression, you need to think about corner-cases. 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. The only potential null is the return value of list(). Thanks for contributing an answer to Stack Overflow! If the pointer is not NULL, see if the assignment occurs only in a branch of a conditional statement.Investigate when that branch does not execute. Ah, gotcha. Which @NotNull Java annotation should I use? Thus we should check > this kstrdup() operation. Dereferencing a null pointer can lead to a denial of service. C# static code analysis: Null pointers should not be dereferenced Products In-IDE IDE extension that lets you fix coding issues before they exist! - the incident has nothing to do with me; can I use this this way? Why does Mister Mxyzptlk need to have a weakness in the comics? At worst, it could expose debugging information that would be useful to an attacker or it could allow an I reordered that code example to do all the checks before allocations. Can you please start a new thread and be more explicit about the issue you are observing. Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. See "Clever Attack Exploits Fully-Patched Linux Kernel" [Goodin 2009] for an example of a code execution exploit that resulted from a null pointer dereference. SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. 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. Why is there a voltage on my HDMI and coaxial cables? What does "Could not find or load main class" mean? My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? Such long getter chains can also be replaced with Optional + map + ifPresent lambda style. )}"); 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. This sounds indeed like a bug in the flow when an exception is raised. S2259: Null pointers should not be dereferenced java tsubasa (Jiaoyang Ma) January 11, 2019, 6:57am 1 versions used (SonarQube, Scanner, language analyzer) SonarQube Version 6.7.2 (build 37468) SonarJava Version 5.9.2 (build 16552) minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). The idea is not to guarantee validity, but to catch a substantial number of problems that could occur. }. Extended Description NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions. positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". Styling contours by colour and by line thickness in QGIS. Im currently using SonarQube version 5.6.6. better way to handle this is to store the result of method invocation in a variable. Null pointer should not be dereferenced . The 2nd NCCE/CS pair seems redundant with the first NCCE/CS pair. Trying to understand how to get this basic Fourier Series. Does Java have support for multiline strings? In Java, a special null value can be assigned to an object reference. very old code or C code being worked into c++ may have functions that expect the user to delete the data. PS: I also tried the code in android studio which uses Lint and got no warnings. This engine is validating execution paths and checking for non-null values or null-check along the way, exploring all the possibilities. The test was added to catch the possibly theoretical situation where the length of input_str was somehow the maximum size for size_t, and adding one to this size in the malloc expression (to allocated space for the trailing null byte) results in an integer overflow. PS: I also tried the code in android studio which uses Lint and got no warnings. Sonar is ok. False-positives are pointed out in other SO posts (1 & 2), where nulls are involved across functions and procedures. It looks like a logic bug, which can cause a memory leaking. Can I tell police to wait and call a lawyer when served with a search warrant? Best to cite C11 s7.24.2.1 here: The memcpy function copies n characters from the object pointed to by s2 into the object pointed to by s1. Finally my method is returning a response with value of restTemplate. Unfortunately the problem is much more complex, and generally unsolvable within standard C. Consider the following example: There's no way f can check whether x points into valid memory or not. 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. The final NCCE is actually more insidious than it seems at first. ability to run any cleanup processes. 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. How do you ensure that a red herring doesn't violate Chekhov's gun? This code also violates ERR33-C. Detect and handle standard library errors. Cause we need throw our own Runtime Exception, well-known methods wont help. (/). // <------- 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. In layman's terms, a null pointer is a pointer to an address in the memory space that does not have a meaningful value and cannot be referenced by the calling program, for whatever reason. 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. 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. ), 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. 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?) By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. 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(). Carnegie Mellon University 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 problem is, I hope this code's result to be <5,3> and <9,6> BUT the console only shows me <5,3> and <9,3>. This will normally lead to an unhandled error, resulting in a segmentation fault. Powered by Discourse, best viewed with JavaScript enabled. Also, the term 'pointer' is bad (but maybe it comes from the FindBugs tool): Java doesn't have pointers, it has references. It's still illegal. Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, S2259: Null pointers should not be dereferenced, find the list of whitelisted methods here, Rule java:S2259: False-positive NullPointerException bug logged when variable is null-checked by an imported method, What is the issue you are observing, in details, What version of SonarSource products you are using, as well as the version of SonarJava.

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