positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. Rule squid:S2259 is based on a Symbolic Execution (SE) engine. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. That is only true if possibleNumbers contains no element.. BTW: none of these warnings are shown by . Software Engineering Institute , NPE : null-, . assert(!invalid(p)); // or whatever, bool invalid(const void *p) { 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. Two null pointers will always be equal to each other. 4. In C# and Java, all reference types can point to null. 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(). [squid:S2259] False positive - "Null pointers should not be dereferenced" Can I tell police to wait and call a lawyer when served with a search warrant? Java Specification Participation Agreement version in use: 2.0. This sounds indeed like a bug in the flow when an exception is raised. 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. U1 merged - It is a great text book for learning about linux devices. 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 */ What sort of strategies would a medieval military use against a fantasy giant? SonarQube - Null Pointer Dereference Issue java simonsirak (Simon Sirak) June 14, 2018, 1:18pm 1 Hi! Avoid Returning null from Methods. Here is our source code: Sign in to download full-size image This code also violates ERR33-C. Detect and handle standard library errors. 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. For example the following program doesn't compile. Using platform-specific means (e.g. Seems the analizer don't recognice the logic with the funcional object Optional. Whats the grammar of "For those whose stories they are"? However, memory allocation > functions such as kstrdup() may fail and returns NULL. 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. 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. [PATCH 1/3] usb: ucsi: Fix NULL pointer deref in ucsi_connector_change() 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. res.getBody() == null || res.getBody().getServiceResult() == null). http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? Does it just mean failing to correctly check if a value is null? 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". It is useful to have a function with portable interface but platform-dependent implementation: extern bool invalid(const void *); To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Passing ownership of something also requires pointers. 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. Just a few words about the rule now. Please explain: Without this, we wont be able to help you. 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. Null pointers should not be dereferenced #1155 - GitHub This will normally lead to an unhandled error, resulting in a segmentation fault. In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. 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. C# static code analysis: Null pointers should not be dereferenced ncdu: What's going on with this second size column? . Is there a proper earth ground point in this switch box? Correct; a null pointer is not a valid pointer for the C library functions. 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. Should trycatch go inside or outside a loop? Alternate Terms Relationships I think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. 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. Doing so will at best cause abrupt program termination, without the What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Making statements based on opinion; back them up with references or personal experience. Sonar false-positive on rule: Null pointers should not be dereferenced So the SIZE_MAX check was unnecessary. Sonar violation: Null pointers should not be dereferenced #7459 - GitHub I suggest that this topic needs to include calloc() and realloc() Refer to Linux man pages online for more enlightenment about malloc(), and friends. 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. We can see that at obj.run(), obj can not be null, but is pointed out by Sonar. SonarLint IntelliJ 4.0.0.2916 Java Rule 'Null pointers should not be dereferenced' I'm getting this fault in the next code when obj can't be null in any scenario. The Clang Static Analyzer already has a checker to find the null pointer dereference in code, however it is not sufficient for higher abstractions such as C++ smart pointers or optionals. The same problem we will have with "Add at least one assertion to this test case." In C++, does dereferencing a nullptr itself cause undefined behaviour The method isNR (minRating) is a helper method that validate among other things, if the object minRating is null public boolean isNR (AgencyRating rating) { return rating == null || isNR (rating.getRatgCaam ()); } When I added the not null validation as sonar suggest. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Now, you can find the list of whitelisted methods here. 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. False fault 'Null pointers should not be dereferenced' using Optional A pointer to null (the 0 memory address) should never be dereferenced/accessed. Is the God of a monotheism necessarily omnipotent? Small typo nit: "such as if i t pointed to freed memory" meant to say "if it" instead (removing whitespace). Null pointer should not be dereferenced . Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, SonarQube - Null Pointer Dereference Issue. When should pointers be checked for NULL in C? Asking for help, clarification, or responding to other answers. The user_data pointer could be invalid in other ways, such as pointing to freed memory. rev2023.3.3.43278. IMHO, the rule title should be changed to something less general. There is a missing check for the return value from . On many platforms, dereferencing a null pointer results inabnormal program termination, but this is not required by the standard. Does a summoned creature play immediately after being summoned by a ready action? Which ensures that the chunkdata pointer is valid, but makes no such check to the user_data pointer. 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. 1. Introduction - Understanding and Using C Pointers [Book] In case the hash algorithm used for the signature is known to the OpenSSL library but the implementation of the hash algorithm is not available the digest initialization will fail. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. Isn't easier just to check valid range of length?