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In C, dereferencing a null pointer is undefined behavior. As for today, the SE engine is able to explore non-overridable methods (static, for instance), when declared in the same file being analyzed. Yeah, I suspect once it's possible to allocate 2+gigs contiguously in amainstream install of a modern OS, we'll see a frenzy of new vulnerabilities come out. 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. 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. Im currently using SonarQube version 5.6.6. better way to handle this is to store the result of method invocation in a variable. Find centralized, trusted content and collaborate around the technologies you use most. Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. 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! 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. What is the point of Thrower's Bandolier? The indicated severity is for this more severe case; on platforms where it is not possible to exploit a null pointer dereference to execute arbitrary code, the actual severity is low. In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. (/). 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. 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. Which ensures that the chunkdata pointer is valid, but makes no such check to the user_data pointer. Styling contours by colour and by line thickness in QGIS. Not the answer you're looking for? This issues is displayed by SonarQube. ), 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. 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. https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx After that, you call res.getBody() again. 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. The fact that you can't pass a null (no object) with a reference parameter can be a reason to use a pointer instead. I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. There are other problems with this code, as is noted in the rule. 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. If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? - the incident has nothing to do with me; can I use this this way? In multithreaded programs, null pointer dereferences can violate cache coherency policies and can cause resource leaks. But even with this, the concerned object it tagged as a possible NullPointerException problem. extern char _etext; The correct idiom is to only allocate storage if the pointer is currently NULL. What are the effects of exceptions on performance in Java? A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. The return value from strchr() is often NULL, but the dev might know that a specific strchr() function call will not return NULL. The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. Avoid Returning null from Methods. http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. sonar-java. 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. This compliant solution eliminates the null pointer deference by initializing sk to tun->sk following the null pointer check. 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. res.getBody() == null || res.getBody().getServiceResult() == null). 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. It could be non-null the first time but not the second time, sonar does not know this. 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. The idea is not to guarantee validity, but to catch a substantial number of problems that could occur. Is a PhD visitor considered as a visiting scholar? C# static code analysis: Null pointers should not be dereferenced Products In-IDE IDE extension that lets you fix coding issues before they exist! EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. best, such an exception will cause abrupt program termination. Good question! This is a matter of style, and also following code walkthrough. () There is a missing check for the return value from . Extended Description NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions. The alert is related to the sonar rule : Null pointers should not be dereferenced. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. // <------- 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. sonarLint (3.2.) A value is checked here to see whether it is null, but this value can't be null because it was previously dereferenced and if it were null a null pointer exception would have occurred at the earlier dereference. 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?) 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. The only potential null is the return value of list(). Using Kolmogorov complexity to measure difficulty of problems? Why is there a voltage on my HDMI and coaxial cables? Passing a null pointer tomemcpy() would produce undefined behavior, even if the number of bytes to copy were 0. This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. Provide a self-contained reproducer (zipped project?) Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. Is there a proper earth ground point in this switch box? Making statements based on opinion; back them up with references or personal experience. This code also violates ERR33-C. Detect and handle standard library errors. Recovering from a blunder I made while emailing a professor. This will normally lead to an unhandled error, resulting in a segmentation fault. I've changed it to say null pointer instead of invalid pointer. which version of SonarQube are you using? The final NCCE is actually more insidious than it seems at first. A pointer is simply a variable that contains a memory address. At 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). When length is zero, it is probably unusable condition for this function. I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. 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. Calls to extension methods are not reported because they can still operate on null values. Null pointers should not be dereferenced. It could be non-null the first time but not the second time, sonar does not know this. 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 there a proper earth ground point in this switch box? sonarqube It means this is illegal: T* p = nullptr; T& r = *p; // illegal NOTE: Please do not email us saying the above works on your particular version of your particular compiler. Find centralized, trusted content and collaborate around the technologies you use most. Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. ability to run any cleanup processes. 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