Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, SonarQube - Null Pointer Dereference Issue. What is the point of Thrower's Bandolier? http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. Alternate Terms Relationships At worst, it could expose debugging information that would be useful to an attacker or it could allow an This is indeed an obvious False Positive from the rule. FindBugs CORRECTNESS - 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. Also, the term 'pointer' is bad (but maybe it comes from the FindBugs tool): Java doesn't have pointers, it has references. Ah, gotcha. 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 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. Dereferencing a null pointer is undefined behavior, typically abnormal program termination. NullPointerException is thrown when program attempts to use an object reference that has the null value. how to handle Sonarlint java:S2259 (Null pointers should not be Styling contours by colour and by line thickness in QGIS. COMP-PROG-MODULE-5-6-REVIEWER.pdf - Pointers to string Correct; a null pointer is not a valid pointer for the C library functions. sonar_etReines-CSDN Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. On many platforms, dereferencing a null pointer results inabnormal program termination, but this is not required by the standard. . Original Java Specification Request (JSR) - Java Community Process 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). which would allow us to systematically observe what you are having. How to get rid of NullPointerException - freeCodeCamp.org To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. 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. SonarJava. After that, you call res.getBody() again. What should you do if somebody passes a null pointer for a parameter Not the answer you're looking for? , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow How do I align things in the following tabular environment? If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. Avoid Returning null from Methods. 9.7 Null pointers - Learn C++ - LearnCpp.com This will normally lead to an unhandled error, resulting in a segmentation fault. Can I tell police to wait and call a lawyer when served with a search warrant? assigning to dereferenced struct pointers Sonar violation: Null pointers should not be dereferenced #7459 - GitHub We can see that at obj.run(), obj can not be null, but is pointed out by Sonar. A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. How can we prove that the supernatural or paranormal doesn't exist? Agreed. rev2023.3.3.43278. static-code-analysis Your assertion is not backed by the wording in the standard, nor by common implementer understanding. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to bypass security measures. Which ensures that the chunkdata pointer is valid, but makes no such check to the user_data pointer. How to tell which packages are held back due to phased updates. Im very new to sonar, is there a way to add methods to the whitelist? the Java one). Issues Components. Isn't easier just to check valid range of length? It looks like a logic bug, which can cause a memory leaking. 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. We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. "After the incident", I started to be more careful not to trip over things. You can use Optional instead. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Making statements based on opinion; back them up with references or personal experience. 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. it could allow an attacker to bypass security measures. And if there is no pointer_default declaration, then the default default is ref. Doing so will cause a NullReferenceException to be thrown. 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. This rule applies to all null pointers, regardless of which function returned them. Asking for help, clarification, or responding to other answers. 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. raiseException() return, Sonar Since you cannot have a variable of type void, the pointer will not point to any data and therefore cannot be dereferenced. The 2nd NCCE/CS pair seems redundant with the first NCCE/CS pair. 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. context.RaiseException , (/) Software project. 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. - the incident has nothing to do with me; can I use this this way? Instead use String.valueOf (object). sonar-java. Reports. This is a matter of style, and also following code walkthrough. (I think you cover that in a different rule.) A pointer to null (the 0 memory address) should never be dereferenced/accessed. At worst, it could expose debugging information that would be useful to an attacker, or 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. Not the answer you're looking for? Asking for help, clarification, or responding to other answers. In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. A reference to Nothing should never be dereferenced/accessed. In the code, we check the not nullity with java.util.Objects.nonNull(). Is there a proper earth ground point in this switch box? 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. Likewise, pointers to freed memory are not valid. We resolved it by adding our tools path in the white list, and repackaging it. 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. , . Void pointers cannot be dereferenced as any other pointer. 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} 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 This sounds indeed like a bug in the flow when an exception is raised. It is still a pointer though, to use it you just have to cast it to another kind of pointer first. What does it mean that a reference must refer to an object, not a dereferenced null pointer? very old code or C code being worked into c++ may have functions that expect the user to delete the data. Null pointer - Wikipedia Now (sonarqube java analyzer version 4.3.0.7717) it's supported and works fine. For the time being, I would unfortunately recommend to mark as False Positive the issue. Check whether a String is not Null and not Empty. C# static code analysis: Null pointers should not be dereferenced Products In-IDE IDE extension that lets you fix coding issues before they exist! Two null pointers will always be equal to each other. I'd guess WG14 has considered these questions, but I haven't until now :). Then we hit memcpy with length 0. Should trycatch go inside or outside a loop? It's a modular system with the . Phew, we're agreed here. The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. How do you ensure that a red herring doesn't violate Chekhov's gun? Connect and share knowledge within a single location that is structured and easy to search. Thanks for contributing an answer to Stack Overflow! 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. I suppose there is a question of "Is a pointer that points to 0 bytes valid?" The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). 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. If you write [ref], then a null pointer is not allowed, but if you write [unique], then a null pointer is permitted. CWE - CWE-476: NULL Pointer Dereference (4.10) - Mitre Corporation 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. Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). 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]. Null pointer should not be dereferenced . Finally, there is the matter of the compliant solution. In multithreaded programs, null pointer dereferences can violate cache coherency policies and can cause resource leaks. And the compliant solution guarantees that the pointer will be valid if the code calls memcpy(). If you call connect() function, it better do the connection, but failing simply because some ptr is NULL is not good behaviour -- failures should . Does a summoned creature play immediately after being summoned by a ready action? It's still illegal. 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. Null Pointer Exception In Java - GeeksforGeeks - A computer science It also adds assertions to document that certain other pointers must not be null. In some situations, however, dereferencing a null pointer can lead to the execution of arbitrary code [Jack 2007,van Sprundel 2006]. All content is copyright protected. Find centralized, trusted content and collaborate around the technologies you use most. , NPE : null-, . Which version of SonarJava plugin do you have? Depending on whether the pointer is valid (i.e. The idea is not to guarantee validity, but to catch a substantial number of problems that could occur. Powered by Discourse, best viewed with JavaScript enabled. How to fix int cannot be dereferenced? Explained by Sharing Culture 3.7. However there is no portable way to verify that the pointer is valid, other than checking for null. Not the answer you're looking for? 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. 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. 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. Is the God of a monotheism necessarily omnipotent? vegan) just to try it, does this inconvenience the caterers and staff? How to avoid dereferencing null pointers in Java - Quora Pointers in C Explained - They're Not as Difficult - freeCodeCamp.org This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. Additionally, if input_str is a null pointer, the call to strlen() dereferences a null pointer, also resulting in undefined behavior. In the simplest case, this function just returns the result of calling kmalloc. Solution 1, it looks like, today's solution tomorrow's problem. I would also guess that pointers that point to the one-past-the-end of an array are also invalid. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? However, memory allocation > functions such as kstrdup() may fail and returns NULL. A bug can cause them never to be reassigned. sometimes FP occurs. java Extended Description NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions. (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). 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. A reference to null should never be dereferenced/accessed. Pointer Arithmetic in c - Unit - 4 1. Define pointer. Explain about the Why does Mister Mxyzptlk need to have a weakness in the comics? When c_str is dereferenced in memcpy(), the program exhibits undefined behavior. You're in a company-managed project. Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". Using Kolmogorov complexity to measure difficulty of problems? The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. When you have a variable of non-primitive type, it is a reference to an object. Passing a null pointer tomemcpy() would produce undefined behavior, even if the number of bytes to copy were 0. 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. That is only true if possibleNumbers contains no element.. BTW: none of these warnings are shown by . Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. 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 . In my experience, there are reasons to check for a NULL pointer other than dereferencing it. Whoops, you're right. public boolean isNameEmpty() { return getName().length() == 0; // Noncompliant; the result of getName() could be null, but isn't null-checked } . 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. https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java. But passing 0 to memcpy() is not one of them. 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). Why void pointer cannot be dereferenced? Explained by Sharing Culture