When B is null, The control reaches inside the main if block only when length of A is 1. sonar-java. 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. Just a few words about the rule now. context.RaiseException , (/) 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. In multithreaded programs, null pointer dereferences can violate cache coherency policies and can cause resource leaks. If malloc() fails, it returns a null pointer that is assigned to c_str. 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). assert(!invalid(p)); // or whatever, bool invalid(const void *p) { How do I align things in the following tabular environment? I reordered that code example to do all the checks before allocations. If that variable hasn't had a reference assigned, it's a null reference, which (for internal/historical reasons) is referred to as a null pointer. The method isNR(minRating) is a helper method that validate among other things, if the object minRating is null. Finally my method is returning a response with value of restTemplate. Your code needs to do something about the possible NullPointerException when some exception is caught, because in this scenario the responseDto will be null. 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 (?,?,?,?,?,?,?,? This will normally lead to an unhandled error, resulting in a segmentation fault. Mutually exclusive execution using std::atomic? If you try to access any member variables or methods with that variable, you are trying to dereference it. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? Alternate Terms Relationships 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 In the code, we check the not nullity with java.util.Objects.nonNull(). New replies are no longer allowed. Minimising the environmental effects of my dyson brain. When B is null, The control reaches inside the main if block only when length of A is 1. 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. . 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. How to deal with "java.lang.OutOfMemoryError: Java heap space" error? , . Pittsburgh, PA 15213-2612 You can use Optional instead. When exploring such methods, the engine then deduces behaviors regarding null-checking (among other things). Not the answer you're looking for? I would also guess that pointers that point to the one-past-the-end of an array are also invalid. Not the answer you're looking for? Powered by Discourse, best viewed with JavaScript enabled. Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. Is the God of a monotheism necessarily omnipotent? Reports. 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 incident has nothing to do with me; can I use this this way? There are many ways to resolve this. io.NotSerializableException : java. uninitialized reference-type class members. The null concept refers to the idea that a pointer can hold a special value that is not equal to another pointer. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. It also adds assertions to document that certain other pointers must not be null. After that, you call res.getBody() again. 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?) Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. (/). Correct; a null pointer is not a valid pointer for the C library functions. Put a new ResponseEntity is wrong because I won't know what will be the answer for the status of http. 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. It could be non-null the first time but not the second time, sonar does not know this. 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. We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". 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). What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. Im very new to sonar, is there a way to add methods to the whitelist? Best to cite C11 s7.24.2.1 here: The memcpy function copies n characters from the object pointed to by s2 into the object pointed to by s1. This compliant solution ensures that the pointer returned by png_malloc() is not null. I think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. How do I align things in the following tabular environment? specifies the length of the array for a function. return p == NULL || (char *)p < &_etext; IMHO, the rule title should be changed to something less general. Appropriate typecasting is necessary. I suppose we can check that that is not null, but we cannot check that it is valid (in any portable way). It's a modular system with the . If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. java In my experience, there are reasons to check for a NULL pointer other than dereferencing it. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. That is only true if possibleNumbers contains no element.. BTW: none of these warnings are shown by . Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). 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. Optimizers are optimizing based on this latitude and have been for years. Find centralized, trusted content and collaborate around the technologies you use most. As for today, the SE engine is able to explore non-overridable methods (static, for instance), when declared in the same file being analyzed. This topic was automatically closed 7 days after the last reply. 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. Making statements based on opinion; back them up with references or personal experience. The only potential null is the return value of list(). Thanks for your relpy. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to bypass security measures. In C# and Java, all reference types can point to 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. sonarlint, sonarLint (3.2.) Batch split images vertically in half, sequentially numbering the output files, Recovering from a blunder I made while emailing a professor. I'd guess null pointers are not valid, even though they point to 0 bytes. Now, you can find the list of whitelisted methods here. The final NCCE is actually more insidious than it seems at first. Check whether a String is not Null and not Empty. 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. A null pointer stores a defined value, but one that is defined by the environment to not be a valid address for any member or object. . In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. Write a semantic patch to nd cases where the result of calling kmalloc is dereferenced with no previous NULL pointer test. (In contrast, the case of passing 0 bytes to malloc is addressed in C11.) Then we hit memcpy with length 0. NULL vs Void Pointer - Null pointer is a value, while void pointer is a type. Asking for help, clarification, or responding to other answers. Software project. This sounds indeed like a bug in the flow when an exception is raised. Thanks for contributing an answer to Stack Overflow! 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. EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Identify where the allocation occurs. Could I capture, and I would be able to glean much security information from the dump? How do you ensure that a red herring doesn't violate Chekhov's gun? It's still illegal. 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. SonarJava. A bug can cause them never to be reassigned. Basically, yes. static-code-analysis Unfortunately, its actual state also has some limitations, like the one you are hitting here. In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. 11 Sep, 2006. When and how should I use a ThreadLocal variable? But when length of A is 1, the control never reaches the else block. A pointer is simply a variable that contains a memory address. I have a sonar alert on this call minRating.getRatgCaam(). 3.7. 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 . An awesome tip to avoid NPE is to return empty strings or empty collections rather than null. So no checking of the length is necessary (besides preventing integer overflow, which the compliant solution does). 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 Carnegie Mellon University By explicitly teaching the C++ standard class behaviors we can make the Analyzer to find more bugs related to modern C++ code. Please direct comments on this JSR to the Spec Lead (s) Team. 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. Is there a single-word adjective for "having exceptionally strong moral principles"? I believe in this case, either expression would work. Hello. NullPointerException is a RuntimeException. It does not point to any area of memory. 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. At worst, it could expose debugging information that would be useful to an attacker or it could allow an False-positives are pointed out in other SO posts (1 & 2), where nulls are involved across functions and procedures. The expected result here is solve the issue with sonarqube. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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 . In the simplest case, this function just returns the result of calling kmalloc. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. Making statements based on opinion; back them up with references or personal experience. }. 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. What is generic pointer? Styling contours by colour and by line thickness in QGIS. The same problem we will have with "Add at least one assertion to this test case." 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. Making statements based on opinion; back them up with references or personal experience. The fact that you can't pass a null (no object) with a reference parameter can be a reason to use a pointer instead. At best, such an exception will cause abrupt program termination. , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow 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. Which ensures that the chunkdata pointer is valid, but makes no such check to the user_data pointer. When a variable is declared as being a pointer to type void, it is known as a generic pointer. Doing so will cause a NullReferenceException to be thrown. What does it mean that a reference must refer to an object, not a dereferenced null pointer? SonarQube null pointers should not be dereferenced on try/catch, Sonarcube :Null pointers should not be dereferenced, How do you get out of a corner when plotting yourself into a corner. sometimes FP occurs. 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. Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. Off by one error: It is the third example. Solution 1, it looks like, today's solution tomorrow's problem. 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. which would allow us to systematically observe what you are having. minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). 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. Note that it doesn't know how to check for non-heap, non-stack. I don't need to do this validation again. Some Interesting Facts: 1) void pointers cannot be dereferenced. Currently I'm working with SonarQube solving issues but I'm facing a trouble to how handle null pointers that shouldn't be dereferenced. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. But when length of A is 1, the control never reaches the else block. (I think you cover that in a different rule.) 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. 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(). So Bar might not be initialized but then the last line of your example should not be evaluated in this case. In particular, ROSE ensures that any pointer returned by malloc(), calloc(), or realloc() is first checked for NULL before being used (otherwise, it is free()-ed). Additionally, if input_str is a null pointer, the call to strlen() dereferences a null pointer, also resulting in undefined behavior. @Tibor SonarQube version 5.6.6, IntelliJ SonarLint plugin 3.0.0.2041, Sonar: Null pointers should not be dereferenced, How Intuit democratizes AI development across teams through reusability. In the meantime, Im locking this thread. This likely means that youre on an ancient version of the Java analyzer. versions used (SonarQube, Scanner, language analyzer) 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.. 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?) Thank you for clarifying your assertion until I understood it properly. Accessing or modifying a null object's field. 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 Things go fine now. What is the point of Thrower's Bandolier? I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. How can we prove that the supernatural or paranormal doesn't exist? To learn more, see our tips on writing great answers. To learn more, see our tips on writing great answers. Using Kolmogorov complexity to measure difficulty of problems? But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. 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. Key here (explains table format and definitions), EXP34-C = Union( CWE-690, list) where list =. 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. 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. What are the effects of exceptions on performance in Java? There is no legitimate reason to dereference a null pointer unless you on a rare system that maps page zero (or you intend your program to crash). At best, such an exception will cause abrupt program termination. I'd guess WG14 has considered these questions, but I haven't until now :). 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. How can we let this pass? But no where in that particular idiom would a NULL pointer necessarily be deferenced. We can see that at obj.run(), obj can not be null, but is pointed out by Sonar. isEmpty(Map map) Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). Whoops, you're right. Such long getter chains can also be replaced with Optional + map + ifPresent lambda style. 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". 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. Thanks for the feedback. I have checked on multiple . 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>. parsing /proc/self/maps under linux) one might find out whether the pointer points into mapped memory, but this is still not a guarantee of validity because it is very coarse-grained see again the above example. name result . To subscribe to this RSS feed, copy and paste this URL into your RSS reader. isEmpty(Collection collection) What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? At worst, it could expose debugging information that would be useful to an attacker, or 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. You need to benchmark. 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! Please explain: Without this, we wont be able to help you. 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. In the case of the ARM and XScale architectures, the 0x0 address is mapped in memory and serves as the exception vector table; consequently, dereferencing 0x0 did not cause an abnormal program termination. Doing so will at best cause abrupt program termination, without the 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. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? sonarlint complains that But what exactly does it mean to "dereference a null pointer"? What sort of strategies would a medieval military use against a fantasy giant? 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. A reference to null should never be dereferenced/accessed. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? When you have a variable of non-primitive type, it is a reference to an object. Does a summoned creature play immediately after being summoned by a ready action? When and how should I use a ThreadLocal variable? 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. We cannot understand how there could be a null pointer exception at the reported line. When length is zero, it is probably unusable condition for this function. In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. Is it possible to create a concave light? 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). 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. 3.Null pointers should not be derefer enced/accessed. This sounds indeed like a bug in the flow when an exception is raised. Trying to understand how to get this basic Fourier Series. extern char _etext; These can be: Invoking a method from a null object. context.RaiseException . Sonar is ok. Sonar can't determine that the helper method did the null validation. This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, SonarQube - Null Pointer Dereference Issue. it could allow an attacker to bypass security measures. Likewise, pointers to freed memory are not valid. Java Specification Participation Agreement version in use: 2.0. For example the following program doesn't compile. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. For the time being, I would unfortunately recommend to mark as False Positive the issue. Thus we should check > this kstrdup() operation. util.regex.Matcher, java - Swing .getParent() . The null pointer check for writing or dereferencing should be a compiler flag or library setting. Recovering from a blunder I made while emailing a professor. Here is our source code: Sign in to download full-size image Does Java have support for multiline strings? Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? That is, sets equivalent to a proper subset via an all-structure-preserving bijection. What does "Could not find or load main class" mean? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. When I added the not null validation as sonar suggest. What is null pointer exception in android. that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. My below code where I'm calling a stored procedure is giving a null pointer exception. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? Can you please start a new thread and be more explicit about the issue you are observing. I suppose there is a question of "Is a pointer that points to 0 bytes valid?" Believing that dereferencing NULL shouldn't crash the system doesn't make it true. Calls to extension methods are not reported because they can still operate on null values. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. 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). Just because something is a pointer does not mean you should call delete . Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. Dereferencing a null pointer is undefined behavior, typically abnormal program termination. Passing ownership of something also requires pointers. It could be non-null the first time but not the second time, sonar does not know this. ability to run any cleanup processes. To learn more, see our tips on writing great answers. Doing so will cause a NullReferenceException to be thrown.
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