null pointers should not be dereferenced

Automated Detection Null pointer dereferences can happen in path-dependent ways. If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? How handle the initialization of "responseDto" without "null" because is throwing the issue on sonar. 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. Doing so will cause a NullReferenceException to be thrown. Write a semantic patch to nd cases where the result of calling kmalloc is dereferenced with no previous NULL pointer test. In C# and Java, all reference types can point to null. rev2023.3.3.43278. What is the point of Thrower's Bandolier? 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. Connect and share knowledge within a single location that is structured and easy to search. Is the God of a monotheism necessarily omnipotent? Using Kolmogorov complexity to measure difficulty of problems? (from res.getBody().getServiceResult() ). Just because something is a pointer does not mean you should call delete . > Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to > the caller site. sonar-java. The above check can't hurt, as I guess you could have a system with a 32-bit size_t that had a ton of memory and had some crazy banking/selector scheme with pointers. Software project. 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. A pointer to null (the 0 memory address) should never be dereferenced/accessed. assert(!invalid(p)); // or whatever, bool invalid(const void *p) { What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. 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. It's still illegal. I suggest that this topic needs to include calloc() and realloc() Refer to Linux man pages online for more enlightenment about malloc(), and friends. 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.) Is it possible to create a concave light? Is it possible to create a concave light? Dereferencing > this null pointer may cause the kernel go wrong. This engine is validating execution paths and checking for non-null values or null-check along the way, exploring all the possibilities. There is no guarantee that subsequent invocations are returning the same value, thats why issue is raised. Now, you can find the list of whitelisted methods here. That is, sets equivalent to a proper subset via an all-structure-preserving bijection. IDE extension that lets you fix coding issues before they exist! This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. With their flexibility, void pointers also bring some constraints. The problem is, I hope this code's result to be <5,3> and <9,6> BUT the console only shows me <5,3> and <9,3>. Which @NotNull Java annotation should I use? 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. () http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. "After the incident", I started to be more careful not to trip over things. We resolved it by adding our tools path in the white list, and repackaging it. 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. Using Kolmogorov complexity to measure difficulty of problems? 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. The chunkdata pointer is later used as a destination argument in a call to memcpy(), resulting in user-defined data overwriting memory starting at address 0. Interactions/interfaces with C can't use references. Null pointers should not be dereferenced. How can we let this pass? Is there a proper earth ground point in this switch box? - the incident has nothing to do with me; can I use this this way? 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. Some Interesting Facts: 1) void pointers cannot be dereferenced. 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]. Trying to understand how to get this basic Fourier Series. When I added the not null validation as sonar suggest. Asking for help, clarification, or responding to other answers. How do you ensure that a red herring doesn't violate Chekhov's gun? I have a sonar alert on this call minRating.getRatgCaam(). What is generic pointer? Thanks for contributing an answer to Stack Overflow! The test was added to catch the possibly theoretical situation where the length of input_str was somehow the maximum size for size_t, and adding one to this size in the malloc expression (to allocated space for the trailing null byte) results in an integer overflow. Thank you for clarifying your assertion until I understood it properly. This rule applies to all null pointers, regardless of which function returned them. specifies the length of the array for a function. I'd guess WG14 has considered these questions, but I haven't until now :). In order to fix this, just do the following: If you are absolutely sure that res.getBody() stays null and is also not modified by another thread, you could also use a //NOSONAR comment in order to suppress the warning. static-code-analysis vegan) just to try it, does this inconvenience the caterers and staff? For the time being, I would unfortunately recommend to mark as False Positive the issue. Then the reading of the buffer via bstr_printf() will then look at the pointer to process the final output. I believe that dereferencing NULL should not crash the system, should not allow a write to a NULL pointer area, but should always set errno, If I am a hacker, could I trap a null failure that would force a memory dump. Trying to understand how to get this basic Fourier Series. . Find centralized, trusted content and collaborate around the technologies you use most. How can we prove that the supernatural or paranormal doesn't exist? Trying to understand how to get this basic Fourier Series. IDE extension that lets you fix coding issues before they exist! And the semantics, as I said, are different. 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 Is there a single-word adjective for "having exceptionally strong moral principles"? Since you cannot have a variable of type void, the pointer will not point to any data and therefore cannot be dereferenced. What does it mean that a reference must refer to an object, not a dereferenced null pointer? String *x, y; X is a pointer to a string, Y is a string & = address of variable/ operator || referencing operator * = value of address || dereferencing operator Pointers = stores memory address as its variables NULL pointer = a constant with a value of zero defined || assigned to null Void pointer = a pointer that is not associated with any data types New operator = denotes a request for . By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Shouldn't the function check all pointers before dereferencing them or passing them to another function? SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. ), 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. Im currently using SonarQube version 5.6.6. better way to handle this is to store the result of method invocation in a variable. Aaron:I suspect we are talking past each other. So we have to check all the arguments before performing any actions. Why do academics stay as adjuncts for years rather than move around? Off by one error: It is the third example. NullPointerException is a RuntimeException. Extended Description NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions. On many platforms, dereferencing a null pointer results inabnormal program termination, but this is not required by the standard. isEmpty(Collection collection) For example the following program doesn't compile. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. Is it possible to rotate a window 90 degrees if it has the same length and width? In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. 1 Answer Sorted by: 2 Your code needs to do something about the possible NullPointerException when some exception is caught, because in this scenario the responseDto will be null. 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. Null pointer should not be dereferenced . uninitialized reference-type class members. 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. 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 */ Seems the analizer don't recognice the logic with the funcional object Optional. SonarJava. In the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. These can be: Invoking a method from a null object. We really appreciate your help. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. The null concept refers to the idea that a pointer can hold a special value that is not equal to another pointer. Finally my method is returning a response with value of restTemplate. null(java.lang.NullPointerException) . As for today, the SE engine is able to explore non-overridable methods (static, for instance), when declared in the same file being analyzed. I have checked on multiple . res.getBody() == null || res.getBody().getServiceResult() == 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" Things go fine now. In Java, a special null value can be assigned to an object reference. Search for vulnerabilities resulting from the violation of this rule on the CERT website. The issue arises when dereferenced pointers are used. 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. Thanks, David! If you preorder a special airline meal (e.g. Pittsburgh, PA 15213-2612 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.. Thus we should check > this kstrdup() operation. Not the answer you're looking for? I think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. Ah, gotcha. EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. When B is null, The control reaches inside the main if block only when length of A is 1. This will normally lead to an unhandled error, resulting in a segmentation fault. False-positives are pointed out in other SO posts (1 & 2), where nulls are involved across functions and procedures. Asking for help, clarification, or responding to other answers. It does not point to any area of memory. Sonar is ok. Sonar can't determine that the helper method did the null validation. positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". 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. In order to fix this, just do the following: BodyType body=res.getBody (); if (body == null || body.getServiceResult () == null) { return; } You can then even reuse body after that. But when length of A is 1, the control never reaches the else block. I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. )}"); Is there a solution to add special characters from software and how to do it, Acidity of alcohols and basicity of amines. 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. But even with this, the concerned object it tagged as a possible NullPointerException problem. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? SonarQube - Null Pointer Dereference Issue java simonsirak (Simon Sirak) June 14, 2018, 1:18pm 1 Hi! The alert is related to the sonar rule : Null pointers should not be dereferenced. SonarQube Version 6.7.2 (build 37468) Connect and share knowledge within a single location that is structured and easy to search. A nonnegative return value represents the number of bytes successfully read (the return value is a "signed size" type, usually the native integer type for the target platform). I guess you could write a proposal to modify the C Standard, but our coding standard is meant to provide guidance for the existing language. "After the incident", I started to be more careful not to trip over things. Why is there a voltage on my HDMI and coaxial cables? I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. 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. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . It could be non-null the first time but not the second time, sonar does not know this. Recovering from a blunder I made while emailing a professor. Does Counterspell prevent from any further spells being cast on a given turn? This code also violates ERR33-C. Detect and handle standard library errors. If you try to access any member variables or methods with that variable, you are trying to dereference it. Reports. I don't need to do this validation again. // <------- 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. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. All content is copyright protected. That makes sense. 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). There are many ways to resolve this. When exploring such methods, the engine then deduces behaviors regarding null-checking (among other things). 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. Pointer members in structs are not checked. The idea is not to guarantee validity, but to catch a substantial number of problems that could occur. , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow We cannot understand how there could be a null pointer exception at the reported line. https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java.