null pointers should not be dereferenced

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. Find centralized, trusted content and collaborate around the technologies you use most. All rights are expressly reserved. IMHO, the rule title should be changed to something less general. 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. (/). By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Sonar violation: Null pointers should not be dereferenced #7459 - GitHub Is there a single-word adjective for "having exceptionally strong moral principles"? CWE - CWE-476: NULL Pointer Dereference (4.10) - Mitre Corporation http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. I don't need to do this validation again. Isn't easier just to check valid range of length? After that, you call res.getBody() again. Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. What are the effects of exceptions on performance in Java? One could argue that all code examples would be redundant with the first pair. ability to run any cleanup processes. The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. 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. It is still a pointer though, to use it you just have to cast it to another kind of pointer first. 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. [JAVA] 3.9 - FP for S2259 Null pointers should not be dereferenced )}"); Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. It could be non-null the first time but not the second time, sonar does not know this. And if there is no pointer_default declaration, then the default default is ref. 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. Im very new to sonar, is there a way to add methods to the whitelist? I have a sonar alert on this call minRating.getRatgCaam(). Search for vulnerabilities resulting from the violation of this rule on the CERT website. This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. It's a modular system with the . Is there a solution to add special characters from software and how to do it, Acidity of alcohols and basicity of amines. Null pointers should not be dereferenced. Null - A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). In C# and Java, all reference types can point to null. In some situations, however, dereferencing a null pointer can lead to the execution of arbitrary code [Jack 2007,van Sprundel 2006]. Recovering from a blunder I made while emailing a professor. Also, the term 'pointer' is bad (but maybe it comes from the FindBugs tool): Java doesn't have pointers, it has references. Shouldn't the function check all pointers before dereferencing them or passing them to another function? This rule applies to all null pointers, regardless of which function returned them. public boolean isNameEmpty() { return getName().length() == 0; // Noncompliant; the result of getName() could be null, but isn't null-checked } . However there is no portable way to verify that the pointer is valid, other than checking for null. In the simplest case, this function just returns the result of calling kmalloc. 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. 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. 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. Pointer members in structs are not checked. int changed to size_t and if size_t parameter's is zero, allocate one word. Thanks for contributing an answer to Stack Overflow! In C++, does dereferencing a nullptr itself cause undefined behaviour Can you please start a new thread and be more explicit about the issue you are observing. - the incident has nothing to do with me; can I use this this way? This compliant solution eliminates the null pointer deference by initializing sk to tun->sk following the null pointer check. Find null smart pointer dereferences with the Clang Static Analyzer I suppose we can check that that is not null, but we cannot check that it is valid (in any portable way). static-code-analysis Java Specification Participation Agreement version in use: 2.0. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. 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. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Using Kolmogorov complexity to measure difficulty of problems? It also uses the unsigned type size_t to pass the length parameter, ensuring that negative values are not passed to func(). As for copy vs pointer/reference - it depends. Reference vs dereference pointers in arguments C++/C it could allow an attacker to bypass security measures. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. What is generic pointer? Since you cannot have a variable of type void, the pointer will not point to any data and therefore cannot be dereferenced. (In contrast, the case of passing 0 bytes to malloc is addressed in C11.) Minimising the environmental effects of my dyson brain. Null pointer should not be dereferenced , 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. 11 Sep, 2006. Find centralized, trusted content and collaborate around the technologies you use most. 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 (?,?,?,?,?,?,?,? 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 issues is displayed by SonarQube. I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. Fixed by #1156 Contributor 94cb5f8 boris-unckel on Jul 28, 2021 9e62550 boris-unckel mentioned this issue on Jul 28, 2021 Closes #1155 - Null pointers should not be dereferenced #1156 Merged How do I align things in the following tabular environment? Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. context.RaiseException . Is it possible to create a concave light? PS: I also tried the code in android studio which uses Lint and got no warnings. This sounds indeed like a bug in the flow when an exception is raised. SonarJava. Sonar false-positive on rule: Null pointers should not 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. Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, SonarQube - Null Pointer Dereference Issue. A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. 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. 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. , NPE : null-, . Doing so will cause a NullReferenceException to be thrown. 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. Instead use String.valueOf (object). I have checked on multiple . How to deal with "java.lang.OutOfMemoryError: Java heap space" error? Solution 1, it looks like, today's solution tomorrow's problem. A pointer to null (the 0 memory address) should never be dereferenced/accessed. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. 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). 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 multithreaded programs, null pointer dereferences can violate cache coherency policies and can cause resource leaks. This will normally lead to an unhandled error, resulting in a segmentation fault. The null pointer check for writing or dereferencing should be a compiler flag or library setting. Likewise, pointers to freed memory are not valid. @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. I believe in this case, either expression would work. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. Is it possible to create a concave light? Analysis of Haiku Operating System (BeOS Family) by PVS-Studio. Part 1 I added an assertion to that compliant code example. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? . I would therefore assert that a platform whose memcpy() did anything besides a no-op when given n=0 and valid source/destination pointers was not C-standards-compliant. 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. 3.7. Thanks for contributing an answer to Stack Overflow! Im currently using SonarQube version 5.6.6. better way to handle this is to store the result of method invocation in a variable. In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. Does a summoned creature play immediately after being summoned by a ready action? SonarQube - Null Pointer Dereference Issue - Sonar Community 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 . The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). A bug can cause them never to be reassigned. Making statements based on opinion; back them up with references or personal experience. . EXP01-J. Do not use a null in a case where an object is required These can be: Invoking a method from a null object. 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. IDE extension that lets you fix coding issues before they exist! Styling contours by colour and by line thickness in QGIS. We can not disable any rule, sonar do validation in "Sonar way" (actual name of profile :) ), so we will need to mark them "Wont fix" each time it appear again in new code. All content is copyright protected. When you have a variable of non-primitive type, it is a reference to an object. Note that it doesn't know how to check for non-heap, non-stack. Connect and share knowledge within a single location that is structured and easy to search. Your code needs to do something about the possible NullPointerException when some exception is caught, because in this scenario the responseDto will be null. What is a NullPointerException, and how do I fix it? We. Thank you for clarifying your assertion until I understood it properly. This is a matter of style, and also following code walkthrough. Doing so will at best cause abrupt program termination, without the Extended Description NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions. squid:S2259 : A "NullPointerException" could be thrown; "dc" is Is null check needed before calling instanceof? 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. The final NCCE is actually more insidious than it seems at first. Share Improve this answer Follow answered Oct 5, 2017 at 16:27 Explain about call by reference with an . Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. name result . SonarQube null pointers should not be dereferenced on try/catch Not the answer you're looking for? SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. To learn more, see our tips on writing great answers. So we have to check all the arguments before performing any actions. And the semantics, as I said, are different. > Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to > the caller site. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Thanks for contributing an answer to Stack Overflow! My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? 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. 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. On many platforms, dereferencing a null pointer results in abnormal program termination, but this is not required by the standard. raiseException() return, Sonar Your assertion is not backed by the wording in the standard, nor by common implementer understanding. Optimizers are optimizing based on this latitude and have been for years. All rights are expressly reserved. 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 */ Unfortunately, its actual state also has some limitations, like the one you are hitting here. java - sonarLint "Null pointers should not be Here is our source code: Sign in to download full-size image Reports. At Recovering from a blunder I made while emailing a professor. Calls to extension methods are not reported because they can still operate on null values. IDE extension that lets you fix coding issues before they exist! 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. Appropriate typecasting is necessary. Key here (explains table format and definitions), EXP34-C = Union( CWE-690, list) where list =. But even with this, the concerned object it tagged as a possible NullPointerException problem. The same problem we will have with "Add at least one assertion to this test case." What sort of strategies would a medieval military use against a fantasy giant? Dereferencing a null pointer can lead to a denial of service. C# static code analysis: HTTP responses should not be vulnerable to I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. 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. Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. rev2023.3.3.43278. 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?) "After the incident", I started to be more careful not to trip over things. In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. Can I tell police to wait and call a lawyer when served with a search warrant? That is only true if possibleNumbers contains no element.. BTW: none of these warnings are shown by . Interactions/interfaces with C can't use references. 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. The problem is that something like %*pbl which reads a bitmask, will save the pointer to the bitmask in the buffer. What is a NullPointerException, and how do I fix it?,What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. sonarlint complains that My main problem is because I'm doing a restTemplate.exchange with try-catch and declaring a variable with null value before the clause try and then using it inside the try. 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Do "superinfinite" sets exist? What is null pointer exception in android. ncdu: What's going on with this second size column? Hello. "After the incident", I started to be more careful not to trip over things. The expected result here is solve the issue with sonarqube. New replies are no longer allowed. When and how should I use a ThreadLocal variable? I feel my situation is not as complicated. We cannot understand how there could be a null pointer exception at the reported line. Off by one error: It is the third example. 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. We have a false positive with the " Null pointers should not be dereferenced -squid:S2259" rule : We have a "NullPointerException" false positive for which we do not know how to solve it. COMP-PROG-MODULE-5-6-REVIEWER.pdf - Pointers to string How to use Slater Type Orbitals as a basis functions in matrix method correctly? I would also guess that pointers that point to the one-past-the-end of an array are also invalid. EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. 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. But when length of A is 1, the control never reaches the else block. We can see that at obj.run(), obj can not be null, but is pointed out by Sonar. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. strongSwan - strongSwan Vulnerability (CVE-2023-26463) Two null pointers will always be equal to each other. 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. java res.getBody() == null || res.getBody().getServiceResult() == null). Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). 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.