sonar_etReines-CSDN Calls to extension methods are not reported because they can still operate on null values. If malloc() fails, it returns a null pointer that is assigned to c_str. 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" Pointer Arithmetic in c - Unit - 4 1. Define pointer. Explain about the best, such an exception will cause abrupt program termination. Avoid Returning null from Methods. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. Issues Components. Can you please start a new thread and be more explicit about the issue you are observing. This code also violates ERR33-C. Detect and handle standard library errors. util.regex.Matcher, java - Swing .getParent() . Rule squid:S2259 is based on a Symbolic Execution (SE) engine. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. 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. When and how should I use a ThreadLocal variable? What sort of strategies would a medieval military use against a fantasy giant? A reference to null should never be dereferenced/accessed. 1 Answer Sorted by: 1 Your code is ok. U1 merged - It is a great text book for learning about linux devices. This solution also ensures that theuser_data pointer is not null. Made code more compliant with other rules. static-code-analysis Interactions/interfaces with C can't use references. Making statements based on opinion; back them up with references or personal experience. You're in a company-managed project. For the time being, I would unfortunately recommend to mark as False Positive the issue. Appropriate typecasting is necessary. Thank you for clarifying your assertion until I understood it properly. FindBugs CORRECTNESS - To create a custom null validation method declare an attribute with name ValidatedNotNullAttribute and mark the parameter that is As for today, the SE engine is able to explore non-overridable methods (static, for instance), when declared in the same file being analyzed. 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. However there is no portable way to verify that the pointer is valid, other than checking for null. Pointer is so confusing : Stack with singly linked list in C - Stack It could be non-null the first time but not the second time, sonar does not know this. 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). Making statements based on opinion; back them up with references or personal experience. which version of SonarQube are you using? This is indeed an obvious False Positive from the rule. context.RaiseException . "After the incident", I started to be more careful not to trip over things. What should you do if somebody passes a null pointer for a parameter Why are physically impossible and logically impossible concepts considered separate in terms of probability? 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. sonarqube 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. There are many ways to resolve this. Just because something is a pointer does not mean you should call delete . This topic was automatically closed 7 days after the last reply. 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Some Interesting Facts: 1) void pointers cannot be dereferenced. Asking for help, clarification, or responding to other answers. return p == NULL || (char *)p < &_etext; Which ensures that the chunkdata pointer is valid, but makes no such check to the user_data pointer. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. Two null pointers will always be equal to each other. Likewise, pointers to freed memory are not valid. Not the answer you're looking for? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. I reordered that code example to do all the checks before allocations. The 4gig boundary will probably be important too with unsigned int in LP64, but since size_t will be 64-bit, there will have to be some truncation that compilers will be able to warn on. In my experience, there are reasons to check for a NULL pointer other than dereferencing it. 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. Not the answer you're looking for? Here is our source code: Sign in to download full-size image Status: Dormant. Whats the grammar of "For those whose stories they are"? squid:S2259 : A "NullPointerException" could be thrown; "dc" is NULL POINTERS SHOULD NOT BE DEREFERENCED - jobhuntley.com 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. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? The same problem we will have with "Add at least one assertion to this test case." If that variable hasn't had a reference assigned, it's a null reference, which (for internal/historical reasons) is referred to as a null pointer. I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. Find centralized, trusted content and collaborate around the technologies you use most. The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. 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. Software Engineering Institute points to memory allocated to the process) and what exactly was allocated there after the public key was freed, this may cause a segmentation fault or even execute code, which could again cause a segmentation fault, but might potentially be under the attacker's control. I added an assertion to that compliant code example. 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. Using platform-specific means (e.g. Is there a single-word adjective for "having exceptionally strong moral principles"? In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. 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. With their flexibility, void pointers also bring some constraints. (from res.getBody().getServiceResult() ). This rule applies to all null pointers, regardless of which function returned them. Im having trouble understanding your problem. The user_data pointer could be invalid in other ways, such as pointing to freed memory. Not the answer you're looking for? At best, such an exception will cause abrupt program termination. I suppose there is a question of "Is a pointer that points to 0 bytes valid?" Recovering from a blunder I made while emailing a professor. VB.NET static code analysis: Null pointers should not be dereferenced In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. How do you ensure that a red herring doesn't violate Chekhov's gun? Provide a self-contained reproducer (zipped project?) We resolved it by adding our tools path in the white list, and repackaging it. A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). To learn more, see our tips on writing great answers. It's still illegal. assert(!invalid(p)); // or whatever, bool invalid(const void *p) { An awesome tip to avoid NPE is to return empty strings or empty collections rather than null. Believing that dereferencing NULL shouldn't crash the system doesn't make it true. One could argue that all code examples would be redundant with the first pair. Should trycatch go inside or outside a loop? Sonar: Null pointers should not be dereferenced - Stack Overflow A nonnegative return value represents the number of bytes successfully read (the return value is a "signed size" type, usually the native integer type for the target platform). assigning to dereferenced struct pointers How do I align things in the following tabular environment? It could be non-null the first time but not the second time, sonar does not know this. [squid:S2259] False positive - "Null pointers should not be dereferenced" Goal Why does Mister Mxyzptlk need to have a weakness in the comics? [RSPEC-2259] - Jira It also adds assertions to document that certain other pointers must not be null. CWE - CWE-476: NULL Pointer Dereference (4.10) - Mitre Corporation 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. SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. EXP01-J. Do not use a null in a case where an object is required If not, this might be a bug. Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. Your assertion is not backed by the wording in the standard, nor by common implementer understanding. S2259: Null pointers should not be dereferenced - Sonar Community When exploring such methods, the engine then deduces behaviors regarding null-checking (among other things). Search for vulnerabilities resulting from the violation of this rule on the CERT website. The fact that you can't pass a null (no object) with a reference parameter can be a reason to use a pointer instead. What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. What are the effects of exceptions on performance in Java? Trying to understand how to get this basic Fourier Series. When a variable is declared as being a pointer to type void, it is known as a generic pointer. The idea is not to guarantee validity, but to catch a substantial number of problems that could occur. That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. java NullPointerException is a RuntimeException. So the SIZE_MAX check was unnecessary. Which @NotNull Java annotation should I use? strongSwan - strongSwan Vulnerability (CVE-2023-26463) The method isNR(minRating) is a helper method that validate among other things, if the object minRating is null. [JAVA] 3.9 - FP for S2259 Null pointers should not be dereferenced This sounds indeed like a bug in the flow when an exception is raised. 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. ability to run any cleanup processes. You can use Optional instead. If you try to access any member variables or methods with that variable, you are trying to dereference it. Sonar is ok. Sonar can't determine that the helper method did the null validation. SonarJava Version 5.9.2 (build 16552). 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. context.RaiseException , (/) A bug can cause them never to be reassigned. Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Null pointers should not be dereferenced #1155 - GitHub My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? (/). At Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. The purpose of a NULL pointer is not to cause a processor exception when it is dereferenced (although that is nice to have for debugging.) In the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. Aaron:I suspect we are talking past each other. The result of calling such a helper function should be . Reports. You can compare a pointer with NULL to test for the special condition. can have the value zero on a call to that function. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? 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 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. And the semantics, as I said, are different. This is a matter of style, and also following code walkthrough. . How can we prove that the supernatural or paranormal doesn't exist? raiseException() return, Sonar This will normally lead to an unhandled error, resulting in a segmentation fault. Connect and share knowledge within a single location that is structured and easy to search. 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". EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. ), 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). ncdu: What's going on with this second size column? At best, such an exception will cause abrupt program termination. 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. Does Java have support for multiline strings? Analysis of Haiku Operating System (BeOS Family) by PVS-Studio. Part 1 COMP-PROG-MODULE-5-6-REVIEWER.pdf - Pointers to string Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. Its purpose is to serve as a special value for a pointer that could indicate a special condition in your program. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. It is still a pointer though, to use it you just have to cast it to another kind of pointer first. 2008-2023 SonarSource S.A., Switzerland. There are other problems with this code, as is noted in the rule. 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. That is, sets equivalent to a proper subset via an all-structure-preserving bijection. sometimes FP occurs. As a result, this noncompliant code example is vulnerable to a null pointer dereference exploit, because null pointer dereferencing can be permitted on several platforms, for example, by using mmap(2) with the MAP_FIXED flag on Linux and Mac OS X, or by using the shmat() POSIX function with the SHM_RND flag [Liu 2009]. 3.7. What does it mean that a reference must refer to an object, not a dereferenced null pointer? Just a few words about the rule 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. Please explain: Without this, we wont be able to help you. res.getBody() == null || res.getBody().getServiceResult() == null). Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. In the meantime, Im locking this thread. 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. rev2023.3.3.43278. I say "theoretical" because I have not successfully produced strings of this length in testing.
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