This is a feature that we are currently heavily working on to be able to switch off such kind of false positives. Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). This is indeed an obvious False Positive from the rule. in above code, 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 Trying to understand how to get this basic Fourier Series. Asking for help, clarification, or responding to other answers. Find centralized, trusted content and collaborate around the technologies you use most. Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, SonarQube - Null Pointer Dereference Issue. Doing so will cause a NullReferenceException to be thrown. The method isNR(minRating) is a helper method that validate among other things, if the object minRating is null. 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]. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. 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. If malloc() fails, it returns a null pointer that is assigned to c_str. Extended Description NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions. Recovering from a blunder I made while emailing a professor. best, such an exception will cause abrupt program termination. Replacing broken pins/legs on a DIP IC package, Bulk update symbol size units from mm to map units in rule-based symbology, How do you get out of a corner when plotting yourself into a corner. If you call connect() function, it better do the connection, but failing simply because some ptr is NULL is not good behaviour -- failures should . 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. New replies are no longer allowed. 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. . ssize_t (*aio_read)(struct kiocb *, char __user *, size_t . Good question! If the pointer is not NULL, see if the assignment occurs only in a branch of a conditional statement.Investigate when that branch does not execute. To learn more, see our tips on writing great answers. The test was added to catch the possibly theoretical situation where the length of input_str was somehow the maximum size for size_t, and adding one to this size in the malloc expression (to allocated space for the trailing null byte) results in an integer overflow. This code also violates ERR33-C. Detect and handle standard library errors. that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. This sounds indeed like a bug in the flow when an exception is raised. It's still illegal. 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 */ Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Finally, there is the matter of the compliant solution. A NULL pointer can be dereferenced when signatures are being verified on PKCS7 signed or signedAndEnveloped data. In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? That is, sets equivalent to a proper subset via an all-structure-preserving bijection. Thanks for your relpy. Find centralized, trusted content and collaborate around the technologies you use most. Whats the grammar of "For those whose stories they are"? 11 Sep, 2006. Cause we need throw our own Runtime Exception, well-known methods wont help. 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. versions used (SonarQube, Scanner, language analyzer) I would also guess that pointers that point to the one-past-the-end of an array are also invalid. 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. By explicitly teaching the C++ standard class behaviors we can make the Analyzer to find more bugs related to modern C++ code. Is there a single-word adjective for "having exceptionally strong moral principles"? It also adds assertions to document that certain other pointers must not be null. With their flexibility, void pointers also bring some constraints. But what exactly does it mean to "dereference a null pointer"? Your assertion is not backed by the wording in the standard, nor by common implementer understanding. A pointer is simply a variable that contains a memory address. NULL vs Uninitialized pointer - An uninitialized pointer stores an undefined value. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. 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). At Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. sonar-java. 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 issue arises when dereferenced pointers are used. The standard will simply copy 0 byteswhich is essentially a no-op. Im very new to sonar, is there a way to add methods to the whitelist? Goal What is a serialVersionUID and why should I use it? Thanks for contributing an answer to Stack Overflow! But passing 0 to memcpy() is not one of them. Batch split images vertically in half, sequentially numbering the output files, Recovering from a blunder I made while emailing a professor. Void pointers cannot be dereferenced as any other pointer. The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. res.getBody() == null || res.getBody().getServiceResult() == null). There is a missing check for the return value from . the Java one). For the time being, I would unfortunately recommend to mark as False Positive the issue. Much like dereferencing a dangling (or wild) pointer leads to undefined behavior, dereferencing a null pointer also leads to undefined behavior. I could've fixed this by changing else to else if (B != null && B.length == 1), but doing so rewards me with warning "condition(B != null && B.length == 1) is always true". 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. Why does the second compliant example permit using possibly-null pointers? You're in a company-managed project. Should trycatch go inside or outside a loop? So we have to check all the arguments before performing any actions. 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. very old code or C code being worked into c++ may have functions that expect the user to delete the data. Made code more compliant with other rules. Does it just mean failing to correctly check if a value is null? Could I capture, and I would be able to glean much security information from the dump? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Agreed. We can see that at obj.run(), obj can not be null, but is pointed out by Sonar. At best, such an exception will cause abrupt program termination. A non-null but invalid pointer passed to memcpy() can indeed cause undefined behavior, but that is not the issue in the noncompliant codethe pointer will either be valid or null. What is null pointer exception in android. Mutually exclusive execution using std::atomic? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. When a variable is declared as being a pointer to type void, it is known as a generic pointer. In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. Reports. raiseException() return, Sonar You need to benchmark. vegan) just to try it, does this inconvenience the caterers and staff? You can use Optional instead. Its purpose is to serve as a special value for a pointer that could indicate a special condition in your program. [4] Aaron:I suspect we are talking past each other. 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.. If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? Is there a proper earth ground point in this switch box? Software Engineering Institute 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. Seems the analizer don't recognice the logic with the funcional object Optional. Is there a solution to add special characters from software and how to do it, Acidity of alcohols and basicity of amines. 4. Put a new ResponseEntity is wrong because I won't know what will be the answer for the status of http. (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). , NPE : null-, . Please explain: Without this, we wont be able to help you. int changed to size_t and if size_t parameter's is zero, allocate one word. I added a comment to explain that SIZE_MAX is the limit of size_t. Then we hit memcpy with length 0. ), Does not guess that return values from malloc(), strchr(), etc., can be NULL (The return value from malloc() is NULL only if there is OOMo and the dev might not care to handle that. There is no guarantee that subsequent invocations are returning the same value, thats why issue is raised. PS: I also tried the code in android studio which uses Lint and got no warnings. When c_str is dereferenced in memcpy(), the program exhibits undefined behavior. Java Specification Participation Agreement version in use: 2.0. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Passing ownership of something also requires pointers. positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". Why does Mister Mxyzptlk need to have a weakness in the comics? The null concept refers to the idea that a pointer can hold a special value that is not equal to another pointer. 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. You can compare a pointer with NULL to test for the special condition. 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). @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. How can this new ban on drag possibly be considered constitutional? 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 (?,?,?,?,?,?,?,? We resolved it by adding our tools path in the white list, and repackaging it. Powered by Discourse, best viewed with JavaScript enabled. Doing so will cause a NullPointerException to be thrown. Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. In the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. Pittsburgh, PA 15213-2612 Which ensures that the chunkdata pointer is valid, but makes no such check to the user_data pointer. There are many ways to resolve this. For example the following program doesn't compile. ability to run any cleanup processes. I suggest that this topic needs to include calloc() and realloc() Refer to Linux man pages online for more enlightenment about malloc(), and friends. Why are physically impossible and logically impossible concepts considered separate in terms of probability? . Dereferencing a null pointer results in undefined behavior. How do you ensure that a red herring doesn't violate Chekhov's gun? The n=0 is a mildly interesting edge case: Clearly a pointer that points to at least one valid byte could be used as the src or dest pointer to a call to memcpy(, 0). SIZE_MAX is the largest possible value that a size_t could take, so it is not possible to have anything larger than SIZE_MAX. can have the value zero on a call to that function. Interactions/interfaces with C can't use references. http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. You can use Optional instead. I suppose there is a question of "Is a pointer that points to 0 bytes valid?" When B is null, The control reaches inside the main if block only when length of A is 1. "After the incident", I started to be more careful not to trip over things. Doing so will cause a NullReferenceException to be thrown. Appropriate typecasting is necessary. 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. 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. What sort of strategies would a medieval military use against a fantasy giant? Which version of SonarJava plugin do you have? SonarJava Version 5.9.2 (build 16552). util.regex.Matcher, java - Swing .getParent() . I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. The correct idiom is to only allocate storage if the pointer is currently NULL. 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. https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java. Basically, yes. But when length of A is 1, the control never reaches the else block. , . 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. Off by one error: It is the third example. Connect and share knowledge within a single location that is structured and easy to search. To learn more, see our tips on writing great answers. This is a matter of style, and also following code walkthrough. 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. Trying to understand how to get this basic Fourier Series. which version of SonarQube are you using? positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. 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 To subscribe to this RSS feed, copy and paste this URL into your RSS reader. This compliant solution eliminates the null pointer deference by initializing sk to tun->sk following the null pointer check. 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(). The fact that you can't pass a null (no object) with a reference parameter can be a reason to use a pointer instead. 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. I don't need to do this validation again. To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. What does "Could not find or load main class" mean? context.RaiseException . However there is no portable way to verify that the pointer is valid, other than checking for null. https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). 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. The alert is related to the sonar rule : Null pointers should not be dereferenced. Do not dereference null pointers Created by Jeffrey Gennari, last modified by Jill Britton on Jan 18, 2023 Dereferencing a null pointer is undefined behavior. ), 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). rev2023.3.3.43278. I added an assertion to that compliant code example. If you preorder a special airline meal (e.g. 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} When exploring such methods, the engine then deduces behaviors regarding null-checking (among other things). SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. 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. ", 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". Please direct comments on this JSR to the Spec Lead (s) Team. 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. , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow In the meantime, Im locking this thread. I reordered that code example to do all the checks before allocations. I think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. Not the answer you're looking for? 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. sometimes FP occurs. We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259.