It is useful to have a function with portable interface but platform-dependent implementation: extern bool invalid(const void *); Recovering from a blunder I made while emailing a professor. 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. // <------- 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. What does it mean that a reference must refer to an object, not a dereferenced null pointer? But even with this, the concerned object it tagged as a possible NullPointerException problem. Fixed by #1156 Contributor 94cb5f8 boris-unckel on Jul 28, 2021 9e62550 boris-unckel mentioned this issue on Jul 28, 2021 Closes #1155 - Null pointers should not be dereferenced #1156 Merged Null pointers should not be dereferenced. raiseException() return, Sonar Such long getter chains can also be replaced with Optional + map + ifPresent lambda style. sonarLint (3.2.) 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. Off by one error: It is the third example. int changed to size_t and if size_t parameter's is zero, allocate one word. 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. 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. > Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to > the caller site. That interpretation of the standard is not supported universally. In C, dereferencing a null pointer is undefined behavior. Powered by Discourse, best viewed with JavaScript enabled. 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. Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. null(java.lang.NullPointerException) . We resolved it by adding our tools path in the white list, and repackaging it. There can be a null pointer type for each pointer type, such as a pointer to a character or a pointer to an integer, although this is . 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 */ An awesome tip to avoid NPE is to return empty strings or empty collections rather than null. 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 (?,?,?,?,?,?,?,? Alternate Terms Relationships But when length of A is 1, the control never reaches the else block. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . Not the answer you're looking for? A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} Connect and share knowledge within a single location that is structured and easy to search. Possible fix: Assign a valid address to the pointer in all branches of the conditional statement.. Pointer can point to dynamically allocated memory. LANG.MEM.NPDLANG.STRUCT.NTADLANG.STRUCT.UPD, Null pointer dereferenceNull test after dereferenceUnchecked parameter dereference, Can detect violations of this rule. SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. In my experience, there are reasons to check for a NULL pointer other than dereferencing it. validated for null in your method declaration with it: 2008-2023 SonarSource S.A., Switzerland. () 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" Good question! Is it possible to create a concave light? java sonarqube This will normally lead to an unhandled error, resulting in a segmentation fault. How do I align things in the following tabular environment? There is no guarantee that subsequent invocations are returning the same value, thats why issue is raised. Provide a self-contained reproducer (zipped project?) , . Thanks, David! It also uses the unsigned type size_t to pass the length parameter, ensuring that negative values are not passed to func(). Can you please start a new thread and be more explicit about the issue you are observing. In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. However, memory allocation > functions such as kstrdup() may fail and returns NULL. (/). If copying takes place between objects that overlap, the behavior is undefined. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, SonarQube null pointers should not be dereferenced on try/catch, How Intuit democratizes AI development across teams through reusability. Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. 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(). By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Hi @Michael! We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. But passing 0 to memcpy() is not one of them. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. What sort of strategies would a medieval military use against a fantasy giant? Since you cannot have a variable of type void, the pointer will not point to any data and therefore cannot be dereferenced. Reports. A NULL pointer can be dereferenced when signatures are being verified on PKCS7 signed or signedAndEnveloped data. Find centralized, trusted content and collaborate around the technologies you use most. Why does the second compliant example permit using possibly-null pointers? 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! All content is copyright protected. If you try to access any member variables or methods with that variable, you are trying to dereference it. 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. How can this new ban on drag possibly be considered constitutional? SonarQube - Null Pointer Dereference Issue java simonsirak (Simon Sirak) June 14, 2018, 1:18pm 1 Hi! Styling contours by colour and by line thickness in QGIS. Optimizers are optimizing based on this latitude and have been for years. So the SIZE_MAX check was unnecessary. Connect and share knowledge within a single location that is structured and easy to search. 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. I don't need to do this validation again. 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). uninitialized reference-type class members. }. res.getBody() == null || res.getBody().getServiceResult() == null). ", 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". 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). My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? JCP version in use: 2.6. Is a PhD visitor considered as a visiting scholar? 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. You can use Optional instead. There is a missing check for the return value from . assert(!invalid(p)); // or whatever, bool invalid(const void *p) { Dereferencing > this null pointer may cause the kernel go wrong. That is why I explicitly check for this in my attempted solution. To learn more, see our tips on writing great answers. When and how should I use a ThreadLocal variable? Depending on whether the pointer is valid (i.e. ), NPD.CHECK.CALL.MIGHTNPD.CHECK.CALL.MUSTNPD.CHECK.MIGHTNPD.CHECK.MUSTNPD.CONST.CALLNPD.CONST.DEREFNPD.FUNC.CALL.MIGHTNPD.FUNC.CALL.MUSTNPD.FUNC.MIGHTNPD.FUNC.MUSTNPD.GEN.CALL.MIGHTNPD.GEN.CALL.MUSTNPD.GEN.MIGHTNPD.GEN.MUSTRNPD.CALLRNPD.DEREF, 45 D, 123 D, 128 D, 129 D, 130 D, 131 D, 652 S, Checks for use of null pointers (rule partially covered). How can we prove that the supernatural or paranormal doesn't exist? rev2023.3.3.43278. I have checked on multiple . The same problem we will have with "Add at least one assertion to this test case." Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. SonarJava Version 5.9.2 (build 16552). I have a sonar alert on this call minRating.getRatgCaam(). Is it suspicious or odd to stand by the gate of a GA airport watching the planes? 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. This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. 11 Sep, 2006. I reordered that code example to do all the checks before allocations. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to bypass security measures. Interactions/interfaces with C can't use references. At best, such an exception will cause abrupt program termination. When a variable is declared as being a pointer to type void, it is known as a generic pointer. Explain about call by reference with an . I suppose we can check that that is not null, but we cannot check that it is valid (in any portable way). Void pointers cannot be dereferenced as any other pointer. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. If you call connect() function, it better do the connection, but failing simply because some ptr is NULL is not good behaviour -- failures should . Is the God of a monotheism necessarily omnipotent? Is there a solution to add special characters from software and how to do it, Acidity of alcohols and basicity of amines. That makes sense. NULL vs Void Pointer - Null pointer is a value, while void pointer is a type. . which would allow us to systematically observe what you are having. Java Specification Participation Agreement version in use: 2.0. 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. At best, such an exception will cause abrupt program termination. 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. 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. io.NotSerializableException : java. How can we let this pass? Minimising the environmental effects of my dyson brain. When exploring such methods, the engine then deduces behaviors regarding null-checking (among other things). By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Im having trouble understanding your problem. I believe that dereferencing NULL should not crash the system, should not allow a write to a NULL pointer area, but should always set errno, If I am a hacker, could I trap a null failure that would force a memory dump. Thanks for contributing an answer to Stack Overflow! 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. In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. How to tell which packages are held back due to phased updates. SonarQube Version 6.7.2 (build 37468) But when length of A is 1, the control never reaches the else block. PS: I also tried the code in android studio which uses Lint and got no warnings. Do "superinfinite" sets exist? It's even called out explicitly in C17 7.24.1p2: Where an argument declared as size_t n specifies the length of the array for a function, n can have the value zero on a call to that function. Do not use a null in a case where an object is required, https://gcc.gnu.org/gcc-4.9/porting_to.html, Prior to 2018-01-12: CERT: Unspecified Relationship, Pointer Casting and Pointer Type Changes [HFC], Dereferencing an out-of-domain pointer [nullref], Section 5.2.18, "Null-Pointer Dereference", Dereferencing null pointers that were not returned by a function. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. 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. You can use Optional instead. Yeah, I suspect once it's possible to allocate 2+gigs contiguously in amainstream install of a modern OS, we'll see a frenzy of new vulnerabilities come out. 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. What is generic pointer? 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. The alert is related to the sonar rule : Null pointers should not be dereferenced. This issues is displayed by SonarQube. 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.. Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. Seems the analizer don't recognice the logic with the funcional object Optional. You're in a company-managed project. I would also guess that pointers that point to the one-past-the-end of an array are also invalid. 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 To create a custom null validation method declare an attribute with name ValidatedNotNullAttribute and mark the parameter that is http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. rev2023.3.3.43278. Unfortunately, its actual state also has some limitations, like the one you are hitting here. Aaron:I suspect we are talking past each other. Now, you can find the list of whitelisted methods here. it could allow an attacker to bypass security measures. Whoops, you're right. Why do academics stay as adjuncts for years rather than move around? Many platforms can support testing for those also. This sounds indeed like a bug in the flow when an exception is raised. (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). But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. This compliant solution eliminates the null pointer deference by initializing sk to tun->sk following the null pointer check. Sonar is ok. Is it possible to create a concave light? In C# and Java, all reference types can point to null. Find centralized, trusted content and collaborate around the technologies you use most. How do you ensure that a red herring doesn't violate Chekhov's gun? I'd guess WG14 has considered these questions, but I haven't until now :). Is there a proper earth ground point in this switch box? Key here (explains table format and definitions), EXP34-C = Union( CWE-690, list) where list =. 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. Just a few words about the rule now. Why are physically impossible and logically impossible concepts considered separate in terms of probability? At SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. This is a feature that we are currently heavily working on to be able to switch off such kind of false positives. - the incident has nothing to do with me; can I use this this way? You can compare a pointer with NULL to test for the special condition. I've changed it to say null pointer instead of invalid pointer. 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. 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. util.regex.Matcher, java - Swing .getParent() . When B is null, The control reaches inside the main if block only when length of A is 1. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. . 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 suggest that this topic needs to include calloc() and realloc() Refer to Linux man pages online for more enlightenment about malloc(), and friends. vegan) just to try it, does this inconvenience the caterers and staff? Please explain: Without this, we wont be able to help you. Thanks for contributing an answer to Stack Overflow! This likely means that youre on an ancient version of the Java analyzer. Correct; a null pointer is not a valid pointer for the C library functions. If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? 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?) Rule squid:S2259 is based on a Symbolic Execution (SE) engine. specifies the length of the array for a function. One could argue that all code examples would be redundant with the first pair. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. 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. However there is no portable way to verify that the pointer is valid, other than checking for null. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? This topic was automatically closed 7 days after the last reply. It is still a pointer though, to use it you just have to cast it to another kind of pointer first. 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. The issue arises when dereferenced pointers are used. This solution also ensures that theuser_data pointer is not null. Are there tables of wastage rates for different fruit and veg? 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. After that, you call res.getBody() again. Can I tell police to wait and call a lawyer when served with a search warrant? That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. Does a summoned creature play immediately after being summoned by a ready action? The final NCCE is actually more insidious than it seems at first. Share Improve this answer Follow answered Oct 5, 2017 at 16:27 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. Is it possible to rotate a window 90 degrees if it has the same length and width? Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. A reference to Nothing should never be dereferenced/accessed. that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. 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. What is null pointer exception in android. IDE extension that lets you fix coding issues before they exist! 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. 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. 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?) sonarlint, sonarLint (3.2.) This code also violates ERR33-C. Detect and handle standard library errors. Hello. Not the answer you're looking for? Using Kolmogorov complexity to measure difficulty of problems? These can be: Invoking a method from a null object. We really appreciate your help. 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). Avoid Returning null from Methods. 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. Coverity Prevent cannot discover all violations of this rule, so further verification is necessary, Detects when NULL is dereferenced (Array of pointers is not checked. How do I align things in the following tabular environment? Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". Issues Components. The method takes a relation name r as input, executes the query "select * from r," and prints the result out in tabular format with the attribute names displayed in the table's header; the attribute names are displayed in the table's header. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA.

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