So Bar might not be initialized but then the last line of your example should not be evaluated in this case. Find centralized, trusted content and collaborate around the technologies you use most. Note that it doesn't know how to check for non-heap, non-stack. References, C++ FAQ By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. What is pointed to should only be deleted if it was created with new. The standard will simply copy 0 byteswhich is essentially a no-op. If copying takes place between objects that overlap, the behavior is undefined. Pittsburgh, PA 15213-2612 COMP-PROG-MODULE-5-6-REVIEWER.pdf - Pointers to string All rights are expressly reserved. ncdu: What's going on with this second size column? So the first execution of ValidateNumber inside the foreach works fine and valid is set to true.The second execution throws the exception and exception is set in the catch-Block.. The user_data pointer could be invalid in other ways, such as pointing to freed memory. As for copy vs pointer/reference - it depends. I'd guess null pointers are not valid, even though they point to 0 bytes. The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. Asking for help, clarification, or responding to other answers. http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. Agreed. Find centralized, trusted content and collaborate around the technologies you use most. Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". Null pointer should not be dereferenced . In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. Essentially, this code and the previous dereference disagree as to whether this value is allowed to be null. NULL vs Uninitialized pointer - An uninitialized pointer stores an undefined value. Likewise, pointers to freed memory are not valid. Things go fine now. sonarqube int changed to size_t and if size_t parameter's is zero, allocate one word. 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. [RSPEC-2259] - Jira "After the incident", I started to be more careful not to trip over things. 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. Sonar violation: Null pointers should not be dereferenced #7459 - GitHub ucsi->connector gets dereferenced by both ucsi_connector_change() and ucsi_resume(), both check for ucsi->connector being NULL in case ucsi_init() has not finished yet; or in case ucsi_init() has failed. Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. 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 Doing so will cause a NullReferenceException to be thrown. 9.7 Null pointers - Learn C++ - LearnCpp.com You can compare a pointer with NULL to test for the special condition. In C/C++ speak, 'dereferencing' simply means getting the object that a pointer . Null pointers should not be dereferenced. There are many ways to resolve this. Solution 1, it looks like, today's solution tomorrow's problem. return p == NULL || (char *)p < &_etext; It's still illegal. isEmpty(Map map) which would allow us to systematically observe what you are having. A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). If not, this might be a bug. A NULL pointer can be dereferenced when signatures are being verified on PKCS7 signed or signedAndEnveloped data. Whoops, you're right. Not the answer you're looking for? {"serverDuration": 214, "requestCorrelationId": "084acdc104f21c51"}, EXP34-C. Do not dereference null pointers, Clever Attack Exploits Fully-Patched Linux Kernel, ERR33-C. Detect and handle standard library errors, one compliant and one non-compliant example, CERT Oracle Secure Coding Standard for Java, EXP01-J. What is a NullPointerException, and how do I fix it?,What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them? Null pointer - Wikipedia In the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. To learn more, see our tips on writing great answers. What is generic pointer? But when length of A is 1, the control never reaches the else block. 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. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. 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. On such a call, a function that locates a character finds no occurrence, a function that compares two character sequences returns zero, and a function that copies characters copies zero characters. [PATCH v2] vsprintf: Do not have bprintf dereference pointers static-code-analysis What is null pointer exception in android Smartadm.ru The alert is related to the sonar rule : Null pointers should not be dereferenced. Why are physically impossible and logically impossible concepts considered separate in terms of probability? // <------- 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. How to convert the address of a dereferenced pointer from C to C# How do I align things in the following tabular environment? 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. NullPointerException is a RuntimeException. But even with this, the concerned object it tagged as a possible NullPointerException problem. We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. Can you please start a new thread and be more explicit about the issue you are observing. The only potential null is the return value of list(). 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. That interpretation of the standard is not supported universally. You're in a company-managed project. Not the answer you're looking for? PDF Fourth Coccinelle Workshop { Exercises When c_str is dereferenced in memcpy(), the program exhibits undefined behavior. 11 Sep, 2006. 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. Search for vulnerabilities resulting from the violation of this rule on the CERT website. Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. 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. Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. sonar_etReines-CSDN 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. Thus we should check > this kstrdup() operation. (C11, S7.24.2.1). 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. attacker to bypass security measures. The result of calling such a helper function should be . That's true. sonarlint complains that Callable statement giving Null Pointer Exception - Oracle Forums If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. Seems the analizer don't recognice the logic with the funcional object Optional. Null Pointer Exception In Java - GeeksforGeeks - A computer science Reports. 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. When exploring such methods, the engine then deduces behaviors regarding null-checking (among other things). So the SIZE_MAX check was unnecessary. [4] 1. Introduction - Understanding and Using C Pointers [Book] We cannot understand how there could be a null pointer exception at the reported line. Void pointers cannot be dereferenced as any other pointer. 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. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. context.RaiseException . Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. At best, such an exception will cause abrupt program termination. You do not have permission to delete messages in this group, Either email addresses are anonymous for this group or you need the view member email addresses permission to view the original message. What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? assert(!invalid(p)); // or whatever, bool invalid(const void *p) { 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. NULL vs Void Pointer - Null pointer is a value, while void pointer is a type. How do you ensure that a red herring doesn't violate Chekhov's gun? Is there a single-word adjective for "having exceptionally strong moral principles"? it could allow an attacker to bypass security measures. This likely means that youre on an ancient version of the Java analyzer. 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 Doing so will cause a NullPointerException to be thrown. Why is there a voltage on my HDMI and coaxial cables? EXP34-C. Do not dereference null pointers - Confluence 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]. 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. It also adds assertions to document that certain other pointers must not be null. Why void pointer cannot be dereferenced? Explained by Sharing Culture 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. I would also guess that pointers that point to the one-past-the-end of an array are also invalid. Thanks for contributing an answer to Stack Overflow! SonarJava. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. Not the answer you're looking for? NullPointerException is thrown when program attempts to use an object reference that has the null value. ), 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). We. Much like dereferencing a dangling (or wild) pointer leads to undefined behavior, dereferencing a null pointer also leads to undefined behavior. uninitialized reference-type class members. One could argue that all code examples would be redundant with the first pair. Connect and share knowledge within a single location that is structured and easy to search. Ah, gotcha. That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. I believe in this case, either expression would work. Find centralized, trusted content and collaborate around the technologies you use most. This noncompliant code example is derived from a real-world example taken from a vulnerable version of the libpng library as deployed on a popular ARM-based cell phone [Jack 2007]. https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java. This is a matter of style, and also following code walkthrough. . Rule squid:S2259 is based on a Symbolic Execution (SE) engine. For example the following program doesn't compile. 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.