This is a matter of style, and also following code walkthrough. Reference vs dereference pointers in arguments C++/C Just a few words about the rule now. This is indeed an obvious False Positive from the rule. https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx Pointers in C Explained - They're Not as Difficult - freeCodeCamp.org FindBugs CORRECTNESS - Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. squid:S2259 : A "NullPointerException" could be thrown; "dc" is How can we prove that the supernatural or paranormal doesn't exist? With their flexibility, void pointers also bring some constraints. int changed to size_t and if size_t parameter's is zero, allocate one word. For example the following program doesn't compile. 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. 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). Using Kolmogorov complexity to measure difficulty of problems? At worst, it could expose debugging information that would be useful to an attacker or it could allow an (from res.getBody().getServiceResult() ). Find centralized, trusted content and collaborate around the technologies you use most. 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. ssize_t (*aio_read)(struct kiocb *, char __user *, size_t . VB.NET static code analysis: Null pointers should not be dereferenced For the time being, I would unfortunately recommend to mark as False Positive the issue. How to get rid of NullPointerException - freeCodeCamp.org 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). Using platform-specific means (e.g. Is there a single-word adjective for "having exceptionally strong moral principles"? Connect and share knowledge within a single location that is structured and easy to search. Thanks for the feedback. You need to benchmark. Haiku is a free and open-source operating system for PC designed to be binary compatible with the BeOS operating system and embodying the basic ideas of BeOS. This is a feature that we are currently heavily working on to be able to switch off such kind of false positives. The null pointer check for writing or dereferencing should be a compiler flag or library setting. Things go fine now. 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. "After the incident", I started to be more careful not to trip over things. 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. Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. We cannot understand how there could be a null pointer exception at the reported line. 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. ), 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). By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. Your code needs to do something about the possible NullPointerException when some exception is caught, because in this scenario the responseDto will be null. You can use Optional instead. 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. I suggest that this topic needs to include calloc() and realloc() Refer to Linux man pages online for more enlightenment about malloc(), and friends. 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. Hello. Null Pointer Recovering from a blunder I made while emailing a professor. If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. OpenSSL Releases Security Update - NHS Digital By explicitly teaching the C++ standard class behaviors we can make the Analyzer to find more bugs related to modern C++ code. can have the value zero on a call to that function. I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. But what exactly does it mean to "dereference a null pointer"? Interactions/interfaces with C can't use references. 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. It is useful to have a function with portable interface but platform-dependent implementation: extern bool invalid(const void *); Likewise, pointers to freed memory are not valid. 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. Can I tell police to wait and call a lawyer when served with a search warrant? You're in a company-managed project. java I added an assertion to that compliant code example. C static code analysis: Null pointers should not be dereferenced But when length of A is 1, the control never reaches the else block. This issues is displayed by SonarQube. Null Pointers - Keil forum - Support forums - Arm Community A pointer to null (the 0 memory address) should never be dereferenced/accessed. What should you do if somebody passes a null pointer for a parameter Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". S2259: Null pointers should not be dereferenced - Sonar Community 1 Answer Sorted by: 1 Your code is ok. Issues Components. 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 Alternate Terms Relationships Provide a self-contained reproducer (zipped project?) Why void pointer cannot be dereferenced? Explained by Sharing Culture Analysis of Haiku Operating System (BeOS Family) by PVS-Studio. Part 1 It also uses the unsigned type size_t to pass the length parameter, ensuring that negative values are not passed to func(). Off by one error: It is the third example. raiseException() return, Sonar best, such an exception will cause abrupt program termination. Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. Find centralized, trusted content and collaborate around the technologies you use most. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? static-code-analysis Is there a proper earth ground point in this switch box? Powered by Discourse, best viewed with JavaScript enabled. What is a NullPointerException, and how do I fix it?,What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them? Software project. That's true. This engine is validating execution paths and checking for non-null values or null-check along the way, exploring all the possibilities. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. I've changed it to say null pointer instead of invalid pointer. Which version of SonarJava plugin do you have? isEmpty(Map map) To learn more, see our tips on writing great answers. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. C# static code analysis: Null pointers should not be dereferenced Thanks for contributing an answer to Stack Overflow! Aaron:I suspect we are talking past each other. 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. Sonar is ok. I have checked on multiple . The method isNR(minRating) is a helper method that validate among other things, if the object minRating is null. The standard will simply copy 0 byteswhich is essentially a no-op. Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. validated for null in your method declaration with it: 2008-2023 SonarSource S.A., Switzerland. My below code where I'm calling a stored procedure is giving a null pointer exception. [SONARJAVA-2808] - Jira - SonarSource Why is there a voltage on my HDMI and coaxial cables? PDF Fourth Coccinelle Workshop { Exercises Unfortunately, its actual state also has some limitations, like the one you are hitting here. "After the incident", I started to be more careful not to trip over things. We resolved it by adding our tools path in the white list, and repackaging it. 3.7. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. If malloc() fails, it returns a null pointer that is assigned to c_str. 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 Connect and share knowledge within a single location that is structured and easy to search. Passing ownership of something also requires pointers. Connect and share knowledge within a single location that is structured and easy to search. Batch split images vertically in half, sequentially numbering the output files, Recovering from a blunder I made while emailing a professor. The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. Dereferencing a null pointer results in undefined behavior. And fwstr > is dereferenced in the following codes. // <------- 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. 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. A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). Doing so will cause a NullReferenceException to be thrown. Good question! Trying to understand how to get this basic Fourier Series. Is it possible to create a concave light? What is null pointer exception in android. Doing so will cause a NullPointerException to be thrown. 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). When B is null, The control reaches inside the main if block only when length of A is 1. 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 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. But no where in that particular idiom would a NULL pointer necessarily be deferenced. A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. Pointer Arithmetic in c - Unit - 4 1. Define pointer. Explain about the The issue arises when dereferenced pointers are used. Some Interesting Facts: 1) void pointers cannot be dereferenced. 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. IDE extension that lets you fix coding issues before they exist! Minimising the environmental effects of my dyson brain. 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. name result . extern char _etext; You're in a company-managed project. At this point we define size as strlen(input_str) + 1. Why pointers are not used in python? Explained by Sharing Culture Please explain: Without this, we wont be able to help you. the Java one). The 2nd NCCE/CS pair seems redundant with the first NCCE/CS pair. How to convert the address of a dereferenced pointer from C to C# 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. What is the point of Thrower's Bandolier? Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? Reports. A pointer is simply a variable that contains a memory address. Appropriate typecasting is necessary. NullPointerException is thrown when program attempts to use an object reference that has the null value. Is a PhD visitor considered as a visiting scholar? assert(!invalid(p)); // or whatever, bool invalid(const void *p) { . 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 (?,?,?,?,?,?,?,? io.NotSerializableException : java. In the simplest case, this function just returns the result of calling kmalloc. 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(). 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. This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. which would allow us to systematically observe what you are having. All rights are expressly reserved. As for copy vs pointer/reference - it depends. But passing 0 to memcpy() is not one of them. What does "Could not find or load main class" mean? 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. In the code, we check the not nullity with java.util.Objects.nonNull(). If you call connect() function, it better do the connection, but failing simply because some ptr is NULL is not good behaviour -- failures should . ncdu: What's going on with this second size column? If you write [ref], then a null pointer is not allowed, but if you write [unique], then a null pointer is permitted. To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. please explain null pointer dereference [Solved] (Java in General forum This rule applies to all null pointers, regardless of which function returned them. Why does the second compliant example permit using possibly-null pointers? 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. Software project. Put a new ResponseEntity is wrong because I won't know what will be the answer for the status of http. Not the answer you're looking for? The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). The null concept refers to the idea that a pointer can hold a special value that is not equal to another pointer. Thus we should check > this kstrdup() operation. Hi Andreas, Thanks for the feedback. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. , . Unlike reference types, pointer types are not tracked by the default garbage . Can you please start a new thread and be more explicit about the issue you are observing. 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. Search for vulnerabilities resulting from the violation of this rule on the CERT website. Now, you can find the list of whitelisted methods here. 11 Sep, 2006. 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.