null pointers should not be dereferenced null pointers should not be dereferenced

Null Pointer The null pointer check for writing or dereferencing should be a compiler flag or library setting. The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). What is the point of Thrower's Bandolier? Dereferencing a null pointer results in undefined behavior. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Pointer is so confusing : Stack with singly linked list in C - Stack Then we hit memcpy with length 0. Shouldn't the function check all pointers before dereferencing them or passing them to another function? [RSPEC-2259] - Jira And the compliant solution guarantees that the pointer will be valid if the code calls memcpy(). Asking for help, clarification, or responding to other answers. http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. Making statements based on opinion; back them up with references or personal experience. . If you preorder a special airline meal (e.g. How can we prove that the supernatural or paranormal doesn't exist? Thanks for contributing an answer to Stack Overflow! When you have a variable of non-primitive type, it is a reference to an object. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. Mutually exclusive execution using std::atomic? 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. assert(!invalid(p)); // or whatever, bool invalid(const void *p) { This is a feature that we are currently heavily working on to be able to switch off such kind of false positives. PDF Fourth Coccinelle Workshop { Exercises You're in a company-managed project. Why void pointer cannot be dereferenced? Explained by Sharing Culture ), 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). 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. java which would allow us to systematically observe what you are having. 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. Such long getter chains can also be replaced with Optional + map + ifPresent lambda style. The libpng library implements its own wrapper to malloc() that returns a null pointer on error or on being passed a 0-byte-length argument. 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>. 2008-2023 SonarSource S.A., Switzerland. 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 The issue is: memcpy() and friends do not explicitly state that a null pointer is a valid pointer value, even if the number of bytes to copy is 0. Software project. Reference vs dereference pointers in arguments C++/C On many platforms, dereferencing a null pointer results inabnormal program termination, but this is not required by the standard. Can you please start a new thread and be more explicit about the issue you are observing. Because null pointer dereferencing is UB, the if (!tun) check can be elided entirely by the optimizer (since the tun->sk implies that tun must be non-null). 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). Trying to understand how to get this basic Fourier Series. S2259: Null pointers should not be dereferenced java tsubasa (Jiaoyang Ma) January 11, 2019, 6:57am 1 versions used (SonarQube, Scanner, language analyzer) SonarQube Version 6.7.2 (build 37468) SonarJava Version 5.9.2 (build 16552) minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). This code also violates ERR33-C. Detect and handle standard library errors. Sonar: Null pointers should not be dereferenced - Stack Overflow 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. ncdu: What's going on with this second size column? Is there a single-word adjective for "having exceptionally strong moral principles"? It also reinforces the notion to the reader that any time you see arithmetic in an allocation expression, you need to think about corner-cases. COMP-PROG-MODULE-5-6-REVIEWER.pdf - Pointers to string When c_str is dereferenced in memcpy(), the program exhibits undefined behavior. To learn more, see our tips on writing great answers. ability to run any cleanup processes. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Analysis of Haiku Operating System (BeOS Family) by PVS-Studio. Part 1 Now (sonarqube java analyzer version 4.3.0.7717) it's supported and works fine. Two null pointers will always be equal to each other. I'd guess null pointers are not valid, even though they point to 0 bytes. This is indeed an obvious False Positive from the rule. rev2023.3.3.43278. Doing so will cause a NullPointerException to be thrown. java - sonarLint "Null pointers should not be Styling contours by colour and by line thickness in QGIS. And the semantics, as I said, are different. Asking for help, clarification, or responding to other answers. Doing so will cause a NullReferenceException to be thrown. Could I capture, and I would be able to glean much security information from the dump? That is only true if possibleNumbers contains no element.. BTW: none of these warnings are shown by . isEmpty(Map map) The expected result here is solve the issue with sonarqube. On many platforms, dereferencing a null pointer results in abnormal program termination, but this is not required by the standard. In the simplest case, this function just returns the result of calling kmalloc. static-code-analysis SIZE_MAX is the largest possible value that a size_t could take, so it is not possible to have anything larger than SIZE_MAX. PS: I also tried the code in android studio which uses Lint and got no warnings. 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 */ I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. The result of calling such a helper function should be . How do I align things in the following tabular environment? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, how to handle Sonarlint java:S2259 (Null pointers should not be dereferenced), How Intuit democratizes AI development across teams through reusability. Trying to understand how to get this basic Fourier Series. MSBuild SonarQube Runner Resharper Plugin receives skipping info errors File not in sonarqube, SonarQube jenkins plugin returns "Server returned HTTP response code: -1, message: 'null' for URL: https://api.github.com/user", SonarQube: Ignore issues in blocks not working with regex, sonarLint complains "Null pointers should not be dereferenced (squid:S2259)" despite that possibility being handled, Java: (false?) Agreed. By explicitly teaching the C++ standard class behaviors we can make the Analyzer to find more bugs related to modern C++ code. This latter use of pointers is a combined boolean/satellite: the pointer being non-null indicates "I have this sister object", and it provides that object. That is, sets equivalent to a proper subset via an all-structure-preserving bijection. Software project. If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? This likely means that youre on an ancient version of the Java analyzer. ROSE does not handle cases where an allocation is assigned to an lvalue that is not a variable (such as a struct member or C++ function call returning a reference), Finds instances where a pointer is checked against NULL and then later dereferenced, Identifies functions that can return a null pointer but are not checked, Identifies code that dereferences a pointer and then checks the pointer against NULL, Can find the instances where NULL is explicitly dereferenced or a pointer is checked againstNULL but then dereferenced anyway. Is there a proper earth ground point in this switch box? After that, you call res.getBody() again. NullPointerException is a RuntimeException. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? How to avoid dereferencing null pointers in Java - Quora This rule applies to all null pointers, regardless of which function returned them. It's a modular system with the . ssize_t (*aio_read)(struct kiocb *, char __user *, size_t . In multithreaded programs, null pointer dereferences can violate cache coherency policies and can cause resource leaks. Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. Null - 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. Replacing broken pins/legs on a DIP IC package, Bulk update symbol size units from mm to map units in rule-based symbology, How do you get out of a corner when plotting yourself into a corner. These can be: Invoking a method from a null object. 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} Null pointers should not be dereferenced (#42) Issues - GitLab IDE extension that lets you fix coding issues before they exist! LANG.MEM.NPDLANG.STRUCT.NTADLANG.STRUCT.UPD, Null pointer dereferenceNull test after dereferenceUnchecked parameter dereference, Can detect violations of this rule. That's true. This solution also ensures that theuser_data pointer is not null. 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. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. What is a NullPointerException, and how do I fix it?,What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them? My below code where I'm calling a stored procedure is giving a null pointer exception. Appropriate typecasting is necessary. In C++, does dereferencing a nullptr itself cause undefined behaviour Callable statement giving Null Pointer Exception - Oracle Forums By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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! 3.Null pointers should not be derefer enced/accessed. There are many ways to resolve this. See the "Null pointer checks may be optimized away more aggressively" section inhttps://gcc.gnu.org/gcc-4.9/porting_to.htmlas an example with one common implementation. - the incident has nothing to do with me; can I use this this way? When I added the not null validation as sonar suggest. 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. 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]. Answered: difference between a void pointer and a | bartleby 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. There is a missing check for the return value from . But when length of A is 1, the control never reaches the else block. That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. If not, this might be a bug. Can I tell police to wait and call a lawyer when served with a search warrant? A non-null but invalid pointer passed to memcpy() can indeed cause undefined behavior, but that is not the issue in the noncompliant codethe pointer will either be valid or null. Using platform-specific means (e.g. How can this new ban on drag possibly be considered constitutional? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. versions used (SonarQube, Scanner, language analyzer) sonarLint (3.2.) Dereferencing > this null pointer may cause the kernel go wrong. 4500 Fifth Avenue The idea is not to guarantee validity, but to catch a substantial number of problems that could occur. The standard will simply copy 0 byteswhich is essentially a no-op. If copying takes place between objects that overlap, the behavior is undefined. How to fix int cannot be dereferenced? Explained by Sharing Culture Sonar false-positive on rule: Null pointers should not be dereferenced (/). Carnegie Mellon University please explain null pointer dereference [Solved] (Java in General forum Is it possible to create a concave light? For the time being, I would unfortunately recommend to mark as False Positive the issue. We cannot understand how there could be a null pointer exception at the reported line. isEmpty(Collection collection) However there is no portable way to verify that the pointer is valid, other than checking for null. If you call connect() function, it better do the connection, but failing simply because some ptr is NULL is not good behaviour -- failures should . 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. In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. Interactions/interfaces with C can't use references. In C, dereferencing a null pointer is undefined behavior. rev2023.3.3.43278. Not the answer you're looking for? Thanks for your relpy. - the incident has nothing to do with me; can I use this this way? SonarQube - Null Pointer Dereference Issue - Sonar Community Hi Andreas, Thanks for the feedback. , NPE : null-, . . At best, such an exception will cause abrupt program termination. C# static code analysis: Null pointers should not be dereferenced Products In-IDE IDE extension that lets you fix coding issues before they exist! Trying to understand how to get this basic Fourier Series. Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. Asking for help, clarification, or responding to other answers. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. And fwstr > is dereferenced in the following codes. For example the following program doesn't compile. You can use Optional instead. extern char _etext; SonarJava Version 5.9.2 (build 16552). Key here (explains table format and definitions), EXP34-C = Union( CWE-690, list) where list =. {"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. 4. 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. So the SIZE_MAX check was unnecessary. Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. When and how should I use a ThreadLocal variable? EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. In some situations, however, dereferencing a null pointer can lead to the execution of arbitrary code [Jack 2007,van Sprundel 2006]. When I scan with sonar-lint in idea, it seams white list is useful, but when use sonar-scanner, always FP, org.springframework.util.CollectionUtils#isEmpty At best, such an exception will cause abrupt program termination. Null Dereference | OWASP Foundation to 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. To learn more, see our tips on writing great answers. Thank you for clarifying your assertion until I understood it properly. If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. I'd guess WG14 has considered these questions, but I haven't until now :). Find centralized, trusted content and collaborate around the technologies you use most. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. In the code, we check the not nullity with java.util.Objects.nonNull(). 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. 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. How to tell which packages are held back due to phased updates. Trying to understand how to get this basic Fourier Series. In my experience, there are reasons to check for a NULL pointer other than dereferencing it. 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. Aaron:I suspect we are talking past each other. We really appreciate your help. HTTP request redirections should not be open to forging attacks Deserialization should not be vulnerable to injection attacks Endpoints should not be vulnerable to reflected cross-site scripting (XSS) attacks "CoSetProxyBlanket" and "CoInitializeSecurity" should not be used Database queries should not be vulnerable to injection attacks It does not point to any area of memory. A reference to null should never be dereferenced/accessed. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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.) That interpretation of the standard is not supported universally. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Dereferencing a null pointer is undefined behavior, typically abnormal program termination. The only potential null is the return value of list(). minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). I have a sonar alert on this call minRating.getRatgCaam(). 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. This topic was automatically closed 7 days after the last reply. U1 merged - It is a great text book for learning about linux devices. ii. Software Engineering Institute Thanks for contributing an answer to Stack Overflow! Sonar is ok. It looks like a logic bug, which can cause a memory leaking. Please explain: Without this, we wont be able to help you. Write a semantic patch to nd cases where the result of calling kmalloc is dereferenced with no previous NULL pointer test. Unfortunately, its actual state also has some limitations, like the one you are hitting here. 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. If the pointer is not NULL, see if the assignment occurs only in a branch of a conditional statement.Investigate when that branch does not execute. A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. Isn't easier just to check valid range of length? C# static code analysis: HTTP responses should not be vulnerable to Whoops, you're right. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. At worst, it could expose debugging information that would be useful to an attacker, or What is null pointer exception in android. Should trycatch go inside or outside a loop? It's even called out explicitly in C17 7.24.1p2: Where an argument declared as size_t n specifies the length of the array for a function, n can have the value zero on a call to that function. Using Kolmogorov complexity to measure difficulty of problems? 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. Possible fix: Assign a valid address to the pointer in all branches of the conditional statement.. Pointer can point to dynamically allocated memory. "After the incident", I started to be more careful not to trip over things. What is a serialVersionUID and why should I use it? Can I tell police to wait and call a lawyer when served with a search warrant? Put a new ResponseEntity is wrong because I won't know what will be the answer for the status of http. Im very new to sonar, is there a way to add methods to the whitelist? positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". SonarQube Version 6.7.2 (build 37468) 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. Original Java Specification Request (JSR) - Java Community Process 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. Some Interesting Facts: 1) void pointers cannot be dereferenced. Things go fine now. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Phew, we're agreed here. 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. Is a PhD visitor considered as a visiting scholar? points to memory allocated to the process) and what exactly was allocated there after the public key was freed, this may cause a segmentation fault or even execute code, which could again cause a segmentation fault, but might potentially be under the attacker's control. What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. name result . ncdu: What's going on with this second size column? An awesome tip to avoid NPE is to return empty strings or empty collections rather than null. raiseException() return, Sonar Minimising the environmental effects of my dyson brain. The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. Null Pointer Exception In Java - GeeksforGeeks - A computer science How do I align things in the following tabular environment? Status: Dormant. 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. At worst, it could expose debugging information that would be useful to an attacker or it could allow an 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. Java Specification Participation Agreement version in use: 2.0. Avoid Returning null from Methods. can have the value zero on a call to that function. https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java.