ssize_t (*aio_read)(struct kiocb *, char __user *, size_t . This compliant solution ensures that the pointer returned by png_malloc() is not null. The idea is not to guarantee validity, but to catch a substantial number of problems that could occur. 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. 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]. Find centralized, trusted content and collaborate around the technologies you use most. attacker to bypass security measures. The alert is related to the sonar rule : Null pointers should not be dereferenced. 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. Powered by Discourse, best viewed with JavaScript enabled. Why do academics stay as adjuncts for years rather than move around? NullPointerException is thrown when program attempts to use an object reference that has the null value. Should trycatch go inside or outside a loop? At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . Passing a null pointer tomemcpy() would produce undefined behavior, even if the number of bytes to copy were 0. To learn more, see our tips on writing great answers. On many platforms, dereferencing a null pointer results in abnormal program termination, but this is not required by the standard. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Mutually exclusive execution using std::atomic? To create a custom null validation method declare an attribute with name ValidatedNotNullAttribute and mark the parameter that is What does "Could not find or load main class" mean? (C11, S7.24.2.1). Connect and share knowledge within a single location that is structured and easy to search. 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! Unlike reference types, pointer types are not tracked by the default garbage . When c_str is dereferenced in memcpy(), the program exhibits undefined behavior. Many platforms can support testing for those also. 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. Is there a proper earth ground point in this switch box? That's true. 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 () Finally my method is returning a response with value of restTemplate. Good question! positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. Asking for help, clarification, or responding to other answers. 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 (?,?,?,?,?,?,?,? sonarlint complains that 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. 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. ncdu: What's going on with this second size column? Correct; a null pointer is not a valid pointer for the C library functions. PS: I also tried the code in android studio which uses Lint and got no warnings. Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. Just a few words about the rule now. 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. My below code where I'm calling a stored procedure is giving a null pointer exception. In C, dereferencing a null pointer is undefined behavior. It is useful to have a function with portable interface but platform-dependent implementation: extern bool invalid(const void *); By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. very old code or C code being worked into c++ may have functions that expect the user to delete the data. 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. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. Why are physically impossible and logically impossible concepts considered separate in terms of probability? Using Kolmogorov complexity to measure difficulty of problems? This sounds indeed like a bug in the flow when an exception is raised. But even with this, the concerned object it tagged as a possible NullPointerException problem. Your assertion is not backed by the wording in the standard, nor by common implementer understanding. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Trying to understand how to get this basic Fourier Series. At Is there a single-word adjective for "having exceptionally strong moral principles"? sonarLint (3.2.) Recovering from a blunder I made while emailing a professor. So no checking of the length is necessary (besides preventing integer overflow, which the compliant solution does). Why does the second compliant example permit using possibly-null pointers? If you preorder a special airline meal (e.g. The value 0 for the number of bytes to copy is not what causes the UB, it's the null pointer value which triggers it. . 1 Answer Sorted by: 1 Your code is ok. 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. 3.Null pointers should not be derefer enced/accessed. To learn more, see our tips on writing great answers. Asking for help, clarification, or responding to other answers. Calls to extension methods are not reported because they can still operate on null values. Which version of SonarJava plugin do you have? Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? 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). At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to bypass security measures. We can get a reference to point to null in the following ways: "uninitialized" reference type variables variables which are initialized with nulls and are assigned their real value afterward. I have a sonar alert on this call minRating.getRatgCaam(). The return value from strchr() is often NULL, but the dev might know that a specific strchr() function call will not return NULL. 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 In the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. , NPE : null-, . 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. specifies the length of the array for a function. Minimising the environmental effects of my dyson brain. https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java. Automated Detection Null pointer dereferences can happen in path-dependent ways. https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx When and how should I use a ThreadLocal variable? After that, you call res.getBody() again. Is it possible to create a concave light? 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. 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. best, such an exception will cause abrupt program termination. Its purpose is to serve as a special value for a pointer that could indicate a special condition in your program. Is a PhD visitor considered as a visiting scholar? 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. I feel my situation is not as complicated. This code also violates ERR33-C. Detect and handle standard library errors. Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. 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. Additionally, if input_str is a null pointer, the call to strlen() dereferences a null pointer, also resulting in undefined behavior. I believe in this case, either expression would work. 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. Solution 1, it looks like, today's solution tomorrow's problem. Is the God of a monotheism necessarily omnipotent? The null pointer check for writing or dereferencing should be a compiler flag or library setting. Which @NotNull Java annotation should I use? In my experience, there are reasons to check for a NULL pointer other than dereferencing it. All content is copyright protected. Is there a proper earth ground point in this switch box? . What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. 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. There is no guarantee that subsequent invocations are returning the same value, thats why issue is raised. Made code more compliant with other rules. name result . versions used (SonarQube, Scanner, language analyzer) It looks like a logic bug, which can cause a memory leaking. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. How to deal with "java.lang.OutOfMemoryError: Java heap space" error? 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. Aaron:I suspect we are talking past each other. So we have to check all the arguments before performing any actions. (in the meantime, in case of any other false-positive suspicion, make sure to check those latest versions as bunch of improvements are regularly released). http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. 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. Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. 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. You're in a company-managed project. It also adds assertions to document that certain other pointers must not be null. Why is there a voltage on my HDMI and coaxial cables? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. New replies are no longer allowed. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. 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. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. Recovering from a blunder I made while emailing a professor. Making statements based on opinion; back them up with references or personal experience. If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. 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. I've changed it to say null pointer instead of invalid pointer. Note that it doesn't know how to check for non-heap, non-stack. ", Eclipse - Sonar S2629 possible false positive with new String, SonarQube null pointers should not be dereferenced on try/catch, getTextContent() through "Null pointers should not be dereferenced". If not, this might be a bug. Batch split images vertically in half, sequentially numbering the output files, Difficulties with estimation of epsilon-delta limit proof, Minimising the environmental effects of my dyson brain. 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. 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 likely means that youre on an ancient version of the Java analyzer. NULL vs Uninitialized pointer - An uninitialized pointer stores an undefined value. However there is no portable way to verify that the pointer is valid, other than checking for null. We resolved it by adding our tools path in the white list, and repackaging it. 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. What are the effects of exceptions on performance in Java? Is it possible to create a concave light? 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. A pointer is simply a variable that contains a memory address. And fwstr > is dereferenced in the following codes. the Java one). Find centralized, trusted content and collaborate around the technologies you use most. The user_data pointer could be invalid in other ways, such as pointing to freed memory. It is still a pointer though, to use it you just have to cast it to another kind of pointer first. Rule squid:S2259 is based on a Symbolic Execution (SE) engine. But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. Null pointer should not be dereferenced . In the simplest case, this function just returns the result of calling kmalloc. Shouldn't the function check all pointers before dereferencing them or passing them to another function? 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. We really appreciate your help. Agreed. 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 */ 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. SonarQube - Null Pointer Dereference Issue java simonsirak (Simon Sirak) June 14, 2018, 1:18pm 1 Hi! Thanks for contributing an answer to Stack Overflow! IDE extension that lets you fix coding issues before they exist! To learn more, see our tips on writing great answers. I suggest that this topic needs to include calloc() and realloc() Refer to Linux man pages online for more enlightenment about malloc(), and friends. Null pointers should not be dereferenced. Using Kolmogorov complexity to measure difficulty of problems? All rights are expressly reserved. java Phew, we're agreed here. Doing so will cause a NullReferenceException to be thrown. This rule applies to all null pointers, regardless of which function returned them. I say "theoretical" because I have not successfully produced strings of this length in testing. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? Batch split images vertically in half, sequentially numbering the output files, Recovering from a blunder I made while emailing a professor. return p == NULL || (char *)p < &_etext; Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. This solution also ensures that theuser_data pointer is not null. 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. I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. 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). sonar-java. Issues Components. How to use Slater Type Orbitals as a basis functions in matrix method correctly? Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy.
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