How to tell which packages are held back due to phased updates. 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. Reports. I don't need to do this validation again. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. I have checked on multiple . The same problem we will have with "Add at least one assertion to this test case." 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. I suppose there is a question of "Is a pointer that points to 0 bytes valid?" SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. This sounds indeed like a bug in the flow when an exception is raised. raiseException() return, Sonar To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 4500 Fifth Avenue
Because null pointer dereferencing is UB, the if (!tun) check can be elided entirely by the optimizer (since the tun->sk implies that tun must be non-null). uninitialized reference-type class members. NullPointerException is thrown when program attempts to use an object reference that has the null value. Because null pointer dereferencing is undefined behavior, the compiler (GCC in this case) can optimize away the if (!tun) check because it is performed after tun->sk is accessed, implying that tun is non-null. In C# and Java, all reference types can point to null. positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". If you call connect() function, it better do the connection, but failing simply because some ptr is NULL is not good behaviour -- failures should . can have the value zero on a call to that function. 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. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. In C/C++ speak, 'dereferencing' simply means getting the object that a pointer . What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Making statements based on opinion; back them up with references or personal experience. 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?) As for today, the SE engine is able to explore non-overridable methods (static, for instance), when declared in the same file being analyzed. This is indeed a false positive because, at time of writing, the sonarqube java analyzer (version 4.2.1 at time of writing) does not support cross procedural analysis and so it is not able to determine that indeed, for the condition to be true, the value of minRating has to be non null. When length is zero, it is probably unusable condition for this function. . (from res.getBody().getServiceResult() ). How to deal with "java.lang.OutOfMemoryError: Java heap space" error? I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. The idea is not to guarantee validity, but to catch a substantial number of problems that could occur. At best, such an exception will cause abrupt program termination. To learn more, see our tips on writing great answers. int changed to size_t and if size_t parameter's is zero, allocate one word. I suggest that this topic needs to include calloc() and realloc() Refer to Linux man pages online for more enlightenment about malloc(), and friends. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? The solution that I recommend is not work with null returns or variables on Java, try to avoid it. Connect and share knowledge within a single location that is structured and easy to search. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. The final NCCE is actually more insidious than it seems at first. The null concept refers to the idea that a pointer can hold a special value that is not equal to another pointer. Is the God of a monotheism necessarily omnipotent? So Bar might not be initialized but then the last line of your example should not be evaluated in this case. Does Counterspell prevent from any further spells being cast on a given turn? This is a matter of style, and also following code walkthrough. A reference to Nothing should never be dereferenced/accessed. Which version of SonarJava plugin do you have? "After the incident", I started to be more careful not to trip over things. But no where in that particular idiom would a NULL pointer necessarily be deferenced. How do you ensure that a red herring doesn't violate Chekhov's gun? When you have a variable of non-primitive type, it is a reference to an object. Some Interesting Facts: 1) void pointers cannot be dereferenced. Doing so will cause a NullPointerException to be thrown. Explain about call by reference with an . 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. 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 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. positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. 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 The correct idiom is to only allocate storage if the pointer is currently NULL. 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. Dereferencing a null pointer is undefined behavior, typically abnormal program termination. 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. By 'valid pointers' I mean that both src and dest pointers are not null and they both point to non-overlapping arrays containing at least n bytes each. We can see that at obj.run(), obj can not be null, but is pointed out by Sonar. 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. And the semantics, as I said, are different. Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. 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. If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. 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. That makes sense. Basically, yes. Doing so will at best cause abrupt program termination, without the All content is copyright protected. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. You can use Optional instead. How handle the initialization of "responseDto" without "null" because is throwing the issue on sonar. Things go fine now. Finally, there is the matter of the compliant solution. 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. Many platforms can support testing for those also. IDE extension that lets you fix coding issues before they exist! Possible fix: Assign a valid address to the pointer in all branches of the conditional statement.. Pointer can point to dynamically allocated memory. sonarqube What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? SonarQube - Null Pointer Dereference Issue java simonsirak (Simon Sirak) June 14, 2018, 1:18pm 1 Hi! Additionally, if input_str is a null pointer, the call to strlen() dereferences a null pointer, also resulting in undefined behavior. Could I capture, and I would be able to glean much security information from the dump? 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. It does not point to any area of memory. A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. But when length of A is 1, the control never reaches the else block. I'd guess null pointers are not valid, even though they point to 0 bytes. 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. 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. Accessing or modifying a null object's field. 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 code also violates ERR33-C. Detect and handle standard library errors. Automated Detection Null pointer dereferences can happen in path-dependent ways. 3.7. 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. . Null pointers should not be dereferenced. 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. Currently I'm working with SonarQube solving issues but I'm facing a trouble to how handle null pointers that shouldn't be dereferenced. util.regex.Matcher, java - Swing .getParent() . 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. 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. What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. This is indeed an obvious False Positive from the rule. Thanks, David! So we have to check all the arguments before performing any actions. Instead use String.valueOf (object). Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? When and how should I use a ThreadLocal variable? What does it mean that a reference must refer to an object, not a dereferenced null pointer? Believing that dereferencing NULL shouldn't crash the system doesn't make it true. 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. Trying to understand how to get this basic Fourier Series. String *x, y; X is a pointer to a string, Y is a string & = address of variable/ operator || referencing operator * = value of address || dereferencing operator Pointers = stores memory address as its variables NULL pointer = a constant with a value of zero defined || assigned to null Void pointer = a pointer that is not associated with any data types New operator = denotes a request for . Whoops, you're right. Off by one error: It is the third example. Hi @Michael! PS: I also tried the code in android studio which uses Lint and got no warnings. Null pointer should not be dereferenced , 11 Sep, 2006. In Java, a special null value can be assigned to an object reference. The return value from strchr() is often NULL, but the dev might know that a specific strchr() function call will not return NULL. In order to fix this, just do the following: If you are absolutely sure that res.getBody() stays null and is also not modified by another thread, you could also use a //NOSONAR comment in order to suppress the warning. How can we prove that the supernatural or paranormal doesn't exist? , . context.RaiseException . See C17 7.1.4p1, which says, in part: Each of the following statements applies unless explicitly stated otherwise in the detailed descriptions that follow: 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 pointerto 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. This solution also ensures that theuser_data pointer is not null. If malloc() fails, it returns a null pointer that is assigned to c_str. Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. 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. When c_str is dereferenced in memcpy(), the program exhibits undefined behavior. Appropriate typecasting is necessary. At worst, it could expose debugging information that would be useful to an attacker or it could allow an 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). The issue arises when dereferenced pointers are used. Thus we should check > this kstrdup() operation. I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. That is why I explicitly check for this in my attempted solution. Asking for help, clarification, or responding to other answers. I've changed it to say null pointer instead of invalid pointer. IMHO, the rule title should be changed to something less general. You're in a company-managed project. If you write [ref], then a null pointer is not allowed, but if you write [unique], then a null pointer is permitted. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Trying to understand how to get this basic Fourier Series. Cause we need throw our own Runtime Exception, well-known methods wont help. SonarJava Version 5.9.2 (build 16552). Please explain: Without this, we wont be able to help you. 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. But when length of A is 1, the control never reaches the else block. Can you please start a new thread and be more explicit about the issue you are observing. In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. Making statements based on opinion; back them up with references or personal experience. Should trycatch go inside or outside a loop? This engine is validating execution paths and checking for non-null values or null-check along the way, exploring all the possibilities. Ah, gotcha. 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. We really appreciate your help. To create a custom null validation method declare an attribute with name ValidatedNotNullAttribute and mark the parameter that is If you preorder a special airline meal (e.g. Is it possible to create a concave light? Just because something is a pointer does not mean you should call delete . Connect and share knowledge within a single location that is structured and easy to search. name result . So you can declare a string t and then add characters to the string with a plus sign : t += 'a'; The code you are having issue with is just moving the pointer to the next character which the foreach is already doing. The user_data pointer could be invalid in other ways, such as pointing to freed memory. () Why does Mister Mxyzptlk need to have a weakness in the comics? Thanks for contributing an answer to Stack Overflow! These can be: Invoking a method from a null object. minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). Does Java have support for multiline strings? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. Find centralized, trusted content and collaborate around the technologies you use most. The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. sometimes FP occurs. . Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? 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 (/). Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Asking for help, clarification, or responding to other answers. - the incident has nothing to do with me; can I use this this way? How to use Slater Type Orbitals as a basis functions in matrix method correctly? // <------- 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. It's still illegal. However, memory allocation > functions such as kstrdup() may fail and returns NULL. http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. This topic was automatically closed 7 days after the last reply. False-positives are pointed out in other SO posts (1 & 2), where nulls are involved across functions and procedures. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. What is null pointer exception in android. It could be non-null the first time but not the second time, sonar does not know this. Its purpose is to serve as a special value for a pointer that could indicate a special condition in your program. Connect and share knowledge within a single location that is structured and easy to search. However there is no portable way to verify that the pointer is valid, other than checking for null. 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 added a comment to explain that SIZE_MAX is the limit of size_t. 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. Such long getter chains can also be replaced with Optional + map + ifPresent lambda style. it could allow an attacker to bypass security measures. Java Specification Participation Agreement version in use: 2.0. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. Sonar is ok. Sonar can't determine that the helper method did the null validation. At this point we define size as strlen(input_str) + 1. Passing a null pointer tomemcpy() would produce undefined behavior, even if the number of bytes to copy were 0. Not the answer you're looking for? Which ensures that the chunkdata pointer is valid, but makes no such check to the user_data pointer. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Check whether a String is not Null and not Empty. This sounds indeed like a bug in the flow when an exception is raised. This rule applies to all null pointers, regardless of which function returned them. Note that it doesn't know how to check for non-heap, non-stack. Do "superinfinite" sets exist? Recovering from a blunder I made while emailing a professor. 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 issue of passing n=0 to memcpy() is distinct from null or invalid pointers. , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. Then we hit memcpy with length 0. And if there is no pointer_default declaration, then the default default is ref. versions used (SonarQube, Scanner, language analyzer) ncdu: What's going on with this second size column? Void pointers cannot be dereferenced as any other pointer. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. It also adds assertions to document that certain other pointers must not be null. Sonar is ok. All rights are expressly reserved. All content is copyright protected. Dereferencing a null pointer results in undefined behavior. Software project. }. To learn more, see our tips on writing great answers. res.getBody() == null || res.getBody().getServiceResult() == null). But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. When exploring such methods, the engine then deduces behaviors regarding null-checking (among other things). rev2023.3.3.43278. Doing so will cause a NullReferenceException to be thrown. 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. Thanks for your relpy. 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 */ 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). How do I align things in the following tabular environment? Thanks for the feedback. in above code, In some situations, however, dereferencing a null pointer can lead to the execution of arbitrary code [Jack 2007,van Sprundel 2006]. What does "Could not find or load main class" mean? Please direct comments on this JSR to the Spec Lead (s) Team. Two null pointers will always be equal to each other. 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. 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! 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. If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? This compliant solution ensures that the pointer returned by png_malloc() is not null. Passing ownership of something also requires pointers.