In C++, does dereferencing a nullptr itself cause undefined behaviour What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Sonar: Null pointers should not be dereferenced - Stack Overflow Thanks for the feedback. 3.7. If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. What is null pointer exception in android Smartadm.ru 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. Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). 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. Doing so will cause a NullReferenceException to be thrown. Making statements based on opinion; back them up with references or personal experience. Likewise, pointers to freed memory are not valid. You can use Optional instead. 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(). Null pointer should not be dereferenced . That is only true if possibleNumbers contains no element.. BTW: none of these warnings are shown by . That is why I explicitly check for this in my attempted solution. Key here (explains table format and definitions), EXP34-C = Union( CWE-690, list) where list =. the Java one). How can I check before my flight that the cloud separation requirements in VFR flight rules are met? It's still illegal. Software project. Accessing or modifying a null object's field. The null pointer check for writing or dereferencing should be a compiler flag or library setting. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Im having trouble understanding your problem. rev2023.3.3.43278. It could be non-null the first time but not the second time, sonar does not know this. Not the answer you're looking for? This rule applies to all null pointers, regardless of which function returned them. This likely means that youre on an ancient version of the Java analyzer. 4. Using Kolmogorov complexity to measure difficulty of problems? My below code where I'm calling a stored procedure is giving a null pointer exception. With their flexibility, void pointers also bring some constraints. What does "Could not find or load main class" mean? Does Java have support for multiline strings? which would allow us to systematically observe what you are having. Reference vs dereference pointers in arguments C++/C sonarqube Java Specification Participation Agreement version in use: 2.0. Do "superinfinite" sets exist? Recovering from a blunder I made while emailing a professor. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? But even with this, the concerned object it tagged as a possible NullPointerException problem. . There are many ways to resolve this. New replies are no longer allowed. The problem is that something like %*pbl which reads a bitmask, will save the pointer to the bitmask in the buffer. Automated Detection Null pointer dereferences can happen in path-dependent ways. By explicitly teaching the C++ standard class behaviors we can make the Analyzer to find more bugs related to modern C++ code. Dereferencing a null pointer results in undefined behavior. 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. res.getBody() == null || res.getBody().getServiceResult() == null). 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. Passing ownership of something also requires pointers. Null - This compliant solution ensures that the pointer returned by png_malloc() is not null. Doing so will cause a NullPointerException to be thrown. Null pointer - Wikipedia 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. Provide a self-contained reproducer (zipped project?) Many platforms can support testing for those also. 412-268-5800, If an argument to a function has an invalid value (such as a value outside the domain of the function, or a pointer outside the address space of the program, or a null pointer, or a pointer. SonarJava. 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. Thank you for clarifying your assertion until I understood it properly. static-code-analysis But passing 0 to memcpy() is not one of them. )}"); What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? CWE-476: NULL Pointer Dereference: 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. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? Optimizers are optimizing based on this latitude and have been for years. (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). In multithreaded programs, null pointer dereferences can violate cache coherency policies and can cause resource leaks. It is still a pointer though, to use it you just have to cast it to another kind of pointer first. 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. At best, such an exception will cause abrupt program termination. > Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to > the caller site. 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. Dereferencing a null pointer is undefined behavior, typically abnormal program termination. 4500 Fifth Avenue 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. 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). Hi @Michael! If malloc() fails, it returns a null pointer that is assigned to c_str. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. In the simplest case, this function just returns the result of calling kmalloc. Making statements based on opinion; back them up with references or personal experience. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. Just because something is a pointer does not mean you should call delete . But when length of A is 1, the control never reaches the else block. How do I align things in the following tabular environment? In my experience, there are reasons to check for a NULL pointer other than dereferencing it. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. FindBugs CORRECTNESS - How handle the initialization of "responseDto" without "null" because is throwing the issue on sonar. Check whether a String is not Null and not Empty. Finally my method is returning a response with value of restTemplate. Pittsburgh, PA 15213-2612 Ah, gotcha. Share Improve this answer Follow answered Oct 5, 2017 at 16:27 This is indeed an obvious False Positive from the rule. If you preorder a special airline meal (e.g. Pointer members in structs are not checked. 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 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. 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. The method isNR (minRating) is a helper method that validate among other things, if the object minRating is null public boolean isNR (AgencyRating rating) { return rating == null || isNR (rating.getRatgCaam ()); } When I added the not null validation as sonar suggest. - the incident has nothing to do with me; can I use this this way? The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. ROSE does not handle cases where an allocation is assigned to an lvalue that is not a variable (such as a struct member or C++ function call returning a reference), Finds instances where a pointer is checked against NULL and then later dereferenced, Identifies functions that can return a null pointer but are not checked, Identifies code that dereferences a pointer and then checks the pointer against NULL, Can find the instances where NULL is explicitly dereferenced or a pointer is checked againstNULL but then dereferenced anyway. What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. I think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. Doing so will cause a NullReferenceException to be thrown. A bug can cause them never to be reassigned. Powered by Discourse, best viewed with JavaScript enabled. 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?) 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). How to get rid of NullPointerException - freeCodeCamp.org void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. Reports. 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. 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. Now, you can find the list of whitelisted methods here. () 1. Introduction - Understanding and Using C Pointers [Book] 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. It also uses the unsigned type size_t to pass the length parameter, ensuring that negative values are not passed to func(). ncdu: What's going on with this second size column? C# static code analysis: HTTP responses should not be vulnerable to There are other problems with this code, as is noted in the rule. can have the value zero on a call to that function. [JAVA] 3.9 - FP for S2259 Null pointers should not be dereferenced That is, sets equivalent to a proper subset via an all-structure-preserving bijection. null(java.lang.NullPointerException) . minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? in above code, Then the reading of the buffer via bstr_printf() will then look at the pointer to process the final output. Styling contours by colour and by line thickness in QGIS. 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>. Powered by Discourse, best viewed with JavaScript enabled. What should you do if somebody passes a null pointer for a parameter But no where in that particular idiom would a NULL pointer necessarily be deferenced. Hello. 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. ncdu: What's going on with this second size column? Its purpose is to serve as a special value for a pointer that could indicate a special condition in your program. context.RaiseException . At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . Then we hit memcpy with length 0. Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. 3.Null pointers should not be derefer enced/accessed. In the code, we check the not nullity with java.util.Objects.nonNull(). Possible fix: Assign a valid address to the pointer in all branches of the conditional statement.. Pointer can point to dynamically allocated memory. Sonar false-positive on rule: Null pointers should not be dereferenced We resolved it by adding our tools path in the white list, and repackaging it. When a variable is declared as being a pointer to type void, it is known as a generic pointer. java In C/C++ speak, 'dereferencing' simply means getting the object that a pointer . 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. Now (sonarqube java analyzer version 4.3.0.7717) it's supported and works fine. Depending on whether the pointer is valid (i.e. Issues Components. Additionally, if input_str is a null pointer, the call to strlen() dereferences a null pointer, also resulting in undefined behavior. In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. There is no guarantee that subsequent invocations are returning the same value, thats why issue is raised. To learn more, see our tips on writing great answers. When I added the not null validation as sonar suggest. So we have to check all the arguments before performing any actions. Is it possible to create a concave light? Does it just mean failing to correctly check if a value is null? All content is copyright protected. Ticket opened : Thanks a lot for the minimalized reproducer ! Hi Andreas, Thanks for the feedback. Search for vulnerabilities resulting from the violation of this rule on the CERT website. A null pointer stores a defined value, but one that is defined by the environment to not be a valid address for any member or object. It looks like a logic bug, which can cause a memory leaking. LANG.MEM.NPDLANG.STRUCT.NTADLANG.STRUCT.UPD, Null pointer dereferenceNull test after dereferenceUnchecked parameter dereference, Can detect violations of this rule. Connect and share knowledge within a single location that is structured and easy to search. 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} Such long getter chains can also be replaced with Optional + map + ifPresent lambda style. io.NotSerializableException : java. PDF Fourth Coccinelle Workshop { Exercises In the meantime, Im locking this thread. Whats the grammar of "For those whose stories they are"?