1. Introduction - Understanding and Using C Pointers [Book] Reports. SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. My question is; is my solution incorrect? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Passing a null pointer tomemcpy() would produce undefined behavior, even if the number of bytes to copy were 0. isEmpty(Collection collection) Null Pointer By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. "After the incident", I started to be more careful not to trip over things. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Issues Components. As for copy vs pointer/reference - it depends. The alert is related to the sonar rule : Null pointers should not be dereferenced. Does Counterspell prevent from any further spells being cast on a given turn? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. In my experience, there are reasons to check for a NULL pointer other than dereferencing it. Dereferencing a null pointer results in undefined behavior. In the simplest case, this function just returns the result of calling kmalloc. public boolean isNameEmpty() { return getName().length() == 0; // Noncompliant; the result of getName() could be null, but isn't null-checked } . Such long getter chains can also be replaced with Optional + map + ifPresent lambda style. Ticket opened : Thanks a lot for the minimalized reproducer ! Pointer Arithmetic in c - Unit - 4 1. Define pointer. Explain about the 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. Small typo nit: "such as if i t pointed to freed memory" meant to say "if it" instead (removing whitespace). Is the God of a monotheism necessarily omnipotent? , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. Off by one error: It is the third example. Finally my method is returning a response with value of restTemplate. 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). sonarlint complains that SonarJava Version 5.9.2 (build 16552). Thanks for contributing an answer to Stack Overflow! Revert Update S2259: "Null pointer dereference" CFG should ignore expressions in Debug.Assert #397 Introduce means to not raise "Expression always true/false" on values that were checked with Debug.Assert. 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. . 3.Null pointers should not be derefer enced/accessed. In C, dereferencing a null pointer is undefined behavior. Is it possible to rotate a window 90 degrees if it has the same length and width? () Please direct comments on this JSR to the Spec Lead (s) Team. validated for null in your method declaration with it: 2008-2023 SonarSource S.A., Switzerland. 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 . 4500 Fifth Avenue Null pointer should not be dereferenced , We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. SonarQube - Null Pointer Dereference Issue - Sonar Community S2259: Null pointers should not be dereferenced - Sonar Community Null pointer should not be dereferenced . To subscribe to this RSS feed, copy and paste this URL into your RSS reader. I would also guess that pointers that point to the one-past-the-end of an array are also invalid. Is there a proper earth ground point in this switch box? All content is copyright protected. 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. 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. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? Write a semantic patch to nd cases where the result of calling kmalloc is dereferenced with no previous NULL pointer test. Review and Fix Illegally Dereferenced Pointer Checks 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. Does it just mean failing to correctly check if a value is null? It is useful to have a function with portable interface but platform-dependent implementation: extern bool invalid(const void *); But even with this, the concerned object it tagged as a possible NullPointerException problem. Which version of SonarJava plugin do you have? Solution 1, it looks like, today's solution tomorrow's problem. Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, SonarQube - Null Pointer Dereference Issue. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. Pittsburgh, PA 15213-2612 IDE extension that lets you fix coding issues before they exist! which version of SonarQube are you using? The issue arises when dereferenced pointers are used. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. 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. In the meantime, Im locking this thread. 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. 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). Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. Whats the grammar of "For those whose stories they are"? To create a custom null validation method declare an attribute with name ValidatedNotNullAttribute and mark the parameter that is ), 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. The correct idiom is to only allocate storage if the pointer is currently NULL. The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. 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 */ So we have to check all the arguments before performing any actions. 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. Automated Detection Null pointer dereferences can happen in path-dependent ways. Good question! C# static code analysis: Null pointers should not be dereferenced Products In-IDE IDE extension that lets you fix coding issues before they exist! In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. The method takes a relation name r as input, executes the query "select * from r," and prints the result out in tabular format with the attribute names displayed in the table's header; the attribute names are displayed in the table's header. If you preorder a special airline meal (e.g. Asking for help, clarification, or responding to other answers. How to fix int cannot be dereferenced? Explained by Sharing Culture which would allow us to systematically observe what you are having. VB.NET static code analysis: Null pointers should not be dereferenced Now, you can find the list of whitelisted methods here. We cannot understand how there could be a null pointer exception at the reported line. Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. IMHO, the rule title should be changed to something less general. False-positives are pointed out in other SO posts (1 & 2), where nulls are involved across functions and procedures. At worst, it could expose debugging information that would be useful to an attacker or it could allow an sonar-java. And the compliant solution guarantees that the pointer will be valid if the code calls memcpy(). uninitialized reference-type class members. 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. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. All rights are expressly reserved. , . I'd guess null pointers are not valid, even though they point to 0 bytes. )}"); // <------- 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. When c_str is dereferenced in memcpy(), the program exhibits undefined behavior. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to bypass security measures. Rule squid:S2259 is based on a Symbolic Execution (SE) engine. To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. 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. Also, the term 'pointer' is bad (but maybe it comes from the FindBugs tool): Java doesn't have pointers, it has references. 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. JCP version in use: 2.6. Do "superinfinite" sets exist? 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?) This compliant solution eliminates the null pointer deference by initializing sk to tun->sk following the null pointer check. This is indeed an obvious False Positive from the rule. Making statements based on opinion; back them up with references or personal experience. 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.
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