null pointers should not be dereferenced

@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. In order to fix this, just do the following: If you are absolutely sure that res.getBody() stays null and is also not modified by another thread, you could also use a //NOSONAR comment in order to suppress the warning. NullPointerException is a RuntimeException. Is there a proper earth ground point in this switch box? // <------- 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. This is a feature that we are currently heavily working on to be able to switch off such kind of false positives. What does it mean that a reference must refer to an object, not a dereferenced null pointer? The only potential null is the return value of list(). 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. . Why is there a voltage on my HDMI and coaxial cables? This is a matter of style, and also following code walkthrough. There are many ways to resolve this. C# static code analysis: Null pointers should not be dereferenced Products In-IDE IDE extension that lets you fix coding issues before they exist! sometimes FP occurs. Is it possible to rotate a window 90 degrees if it has the same length and width? But passing 0 to memcpy() is not one of them. How can we prove that the supernatural or paranormal doesn't exist? 4. It is useful to have a function with portable interface but platform-dependent implementation: extern bool invalid(const void *); sonarqube The user_data pointer could be invalid in other ways, such as pointing to freed memory. If that variable hasn't had a reference assigned, it's a null reference, which (for internal/historical reasons) is referred to as a null pointer. Alternate Terms Relationships The fact that you can't pass a null (no object) with a reference parameter can be a reason to use a pointer instead. A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). 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. When you have a variable of non-primitive type, it is a reference to an object. points to memory allocated to the process) and what exactly was allocated there after the public key was freed, this may cause a segmentation fault or even execute code, which could again cause a segmentation fault, but might potentially be under the attacker's control. The alert is related to the sonar rule : Null pointers should not be dereferenced. Your assertion is not backed by the wording in the standard, nor by common implementer understanding. Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". So the first execution of ValidateNumber inside the foreach works fine and valid is set to true.The second execution throws the exception and exception is set in the catch-Block.. Many platforms can support testing for those also. that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. versions used (SonarQube, Scanner, language analyzer) Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. sonar-java. 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. Obviously the value of that pointer could have changed since the . I suppose we can check that that is not null, but we cannot check that it is valid (in any portable way). PS: I also tried the code in android studio which uses Lint and got no warnings. 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. In my experience, there are reasons to check for a NULL pointer other than dereferencing it. Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. Isn't easier just to check valid range of length? Appropriate typecasting is necessary. IDE extension that lets you fix coding issues before they exist! At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to bypass security measures. How to deal with "java.lang.OutOfMemoryError: Java heap space" error? How can we let this pass? positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". 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. Using Kolmogorov complexity to measure difficulty of problems? How can this new ban on drag possibly be considered constitutional? Carnegie Mellon University What sort of strategies would a medieval military use against a fantasy giant? Find centralized, trusted content and collaborate around the technologies you use most. Check whether a String is not Null and not Empty. Then the reading of the buffer via bstr_printf() will then look at the pointer to process the final output. Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). 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. Things go fine now. 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. Finally, there is the matter of the compliant solution. in above code, When a variable is declared as being a pointer to type void, it is known as a generic pointer. Connect and share knowledge within a single location that is structured and easy to search. 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. 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 generic pointer? Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? With their flexibility, void pointers also bring some constraints. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. sonarlint complains that Which ensures that the chunkdata pointer is valid, but makes no such check to the user_data pointer. 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 (?,?,?,?,?,?,?,? positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. Thanks for contributing an answer to Stack Overflow! It's still illegal. Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. Good question! Status: Dormant. It is still a pointer though, to use it you just have to cast it to another kind of pointer first. One could argue that all code examples would be redundant with the first pair. The result of calling such a helper function should be . > Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to > the caller site. Much like dereferencing a dangling (or wild) pointer leads to undefined behavior, dereferencing a null pointer also leads to undefined behavior. context.RaiseException , (/) 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. 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. If you preorder a special airline meal (e.g. java In multithreaded programs, null pointer dereferences can violate cache coherency policies and can cause resource leaks. To create a custom null validation method declare an attribute with name ValidatedNotNullAttribute and mark the parameter that is What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Sonar: Null pointers should not be dereferenced, Why should Java 8's Optional not be used in arguments, Sonar alert : "private" methods that don't access instance data should be "static", sonarLint complains "Null pointers should not be dereferenced (squid:S2259)" despite that possibility being handled, Java: (false?) Trying to understand how to get this basic Fourier Series. 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. IMHO, the rule title should be changed to something less general. SonarJava Version 5.9.2 (build 16552). Not the answer you're looking for? Dereferencing a null pointer results in undefined behavior. 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. And the compliant solution guarantees that the pointer will be valid if the code calls memcpy(). 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" Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} This is indeed a false positive because, at time of writing, the sonarqube java analyzer (version 4.2.1 at time of writing) does not support cross procedural analysis and so it is not able to determine that indeed, for the condition to be true, the value of minRating has to be non null. rev2023.3.3.43278. }. 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). Thus we should check > this kstrdup() operation. That is only true if possibleNumbers contains no element.. BTW: none of these warnings are shown by . 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>. . Correct; a null pointer is not a valid pointer for the C library functions. The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. Dereferencing a null pointer is undefined behavior, typically abnormal program termination. In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. context.RaiseException . How do I align things in the following tabular environment? Passing a null pointer tomemcpy() would produce undefined behavior, even if the number of bytes to copy were 0. This code also violates ERR33-C. Detect and handle standard library errors. EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. 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. In C/C++ speak, 'dereferencing' simply means getting the object that a pointer . validated for null in your method declaration with it: 2008-2023 SonarSource S.A., Switzerland. In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. And fwstr > is dereferenced in the following codes. If not, this might be a bug. In the code, we check the not nullity with java.util.Objects.nonNull(). Now (sonarqube java analyzer version 4.3.0.7717) it's supported and works fine. Its purpose is to serve as a special value for a pointer that could indicate a special condition in your program. Dereferencing a null pointer can lead to a denial of service. SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. Powered by Discourse, best viewed with JavaScript enabled. Here is our source code: Sign in to download full-size image Connect and share knowledge within a single location that is structured and easy to search. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. But even with this, the concerned object it tagged as a possible NullPointerException problem. 2008-2023 SonarSource S.A., Switzerland. This rule applies to all null pointers, regardless of which function returned them. 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.