SonarQube - Null Pointer Dereference Issue java simonsirak (Simon Sirak) June 14, 2018, 1:18pm 1 Hi! NULL vs Void Pointer - Null pointer is a value, while void pointer is a type. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. How do I align things in the following tabular environment? What is the point of Thrower's Bandolier? 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. For the time being, I would unfortunately recommend to mark as False Positive the issue. What sort of strategies would a medieval military use against a fantasy giant? 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. Because null pointer dereferencing is undefined behavior, the compiler (GCC in this case) can optimize away the if (!tun) check because it is performed after tun->sk is accessed, implying that tun is non-null. rev2023.3.3.43278. It does not point to any area of memory. A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). Im very new to sonar, is there a way to add methods to the whitelist? 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.) Recovering from a blunder I made while emailing a professor. As for copy vs pointer/reference - it depends. Which ensures that the chunkdata pointer is valid, but makes no such check to the user_data pointer. Connect and share knowledge within a single location that is structured and easy to search. New replies are no longer allowed. 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). 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. Fix S2583/S2589 FP: On null check if instance is used in try block - GitHub But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. strongSwan - strongSwan Vulnerability (CVE-2023-26463) return p == NULL || (char *)p < &_etext; In C++, does dereferencing a nullptr itself cause undefined behaviour By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. But when length of A is 1, the control never reaches the else block. Is it possible to create a concave light? 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. sonarLint (3.2.) This compliant solution eliminates the null pointer deference by initializing sk to tun->sk following the null pointer check. SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. Making statements based on opinion; back them up with references or personal experience. Doing so will cause a NullReferenceException to be thrown. 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. Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. It also adds assertions to document that certain other pointers must not be null. This compliant solution ensures that the pointer returned by png_malloc() is not null. Then we hit memcpy with length 0. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? When you have a variable of non-primitive type, it is a reference to an object. This is a feature that we are currently heavily working on to be able to switch off such kind of false positives. ncdu: What's going on with this second size column? This issues is displayed by SonarQube. So we have to check all the arguments before performing any actions. Sonar is ok. Sonar can't determine that the helper method did the null validation. Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. 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. 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. On the command prompt, the same arguments work and the record is added in db but not when I call the stored procedure from inside java program CallableStatement insertStat = db_conn.prepareCall (" {call InsertCourses (?,?,?,?,?,?,?,? You can use Optional instead. Powered by Discourse, best viewed with JavaScript enabled. I have a sonar alert on this call minRating.getRatgCaam(). For example the following program doesn't compile. Null pointer should not be dereferenced . 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, 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. 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?) Software project. 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} Is there a proper earth ground point in this switch box? The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. EXP34-C. Do not dereference null pointers - Confluence But no where in that particular idiom would a NULL pointer necessarily be deferenced. My below code where I'm calling a stored procedure is giving a null pointer exception. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Such long getter chains can also be replaced with Optional + map + ifPresent lambda style. squid:S2259 : A "NullPointerException" could be thrown; "dc" is And the semantics, as I said, are different. What is a NullPointerException, and how do I fix it?,What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them? At best, such an exception will cause abrupt program termination. Im having trouble understanding your problem. All rights are expressly reserved. Null pointers should not be dereferenced (#42) Issues - GitLab 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. To create a custom null validation method declare an attribute with name ValidatedNotNullAttribute and mark the parameter that is And if there is no pointer_default declaration, then the default default is ref. I think that checking for user_data being NULL would be an improvement to the CS so long as there is an explicit mention that user_data being NULL is invalid even if length == 0. An awesome tip to avoid NPE is to return empty strings or empty collections rather than null. best, such an exception will cause abrupt program termination. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to bypass security measures. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? Note that it doesn't know how to check for non-heap, non-stack. 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. 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). 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 . 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. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. Essentially, this code and the previous dereference disagree as to whether this value is allowed to be null. Phew, we're agreed here. You need to benchmark. Dereferencing > this null pointer may cause the kernel go wrong. 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. How do you ensure that a red herring doesn't violate Chekhov's gun? Off by one error: It is the third example. Why does Mister Mxyzptlk need to have a weakness in the comics? Some Interesting Facts: 1) void pointers cannot be dereferenced. 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. One could argue that all code examples would be redundant with the first pair. Automated Detection Null pointer dereferences can happen in path-dependent ways. "After the incident", I started to be more careful not to trip over things. Why do academics stay as adjuncts for years rather than move around? However, memory allocation > functions such as kstrdup() may fail and returns NULL. 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. Things go fine now. PDF Fourth Coccinelle Workshop { Exercises very old code or C code being worked into c++ may have functions that expect the user to delete the data. Just a few words about the rule now. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. Why are physically impossible and logically impossible concepts considered separate in terms of probability?