Thanks for your relpy. Void pointers cannot be dereferenced as any other pointer. void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. I say "theoretical" because I have not successfully produced strings of this length in testing. I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. Is there a single-word adjective for "having exceptionally strong moral principles"? In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. I've changed it to say null pointer instead of invalid pointer. Interactions/interfaces with C can't use references. How can we prove that the supernatural or paranormal doesn't exist? SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. What is the point of Thrower's Bandolier? Phew, we're agreed here. It also adds assertions to document that certain other pointers must not be null. Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. All rights are expressly reserved. Explain about call by reference with an . NULL vs Void Pointer - Null pointer is a value, while void pointer is a type. Which @NotNull Java annotation should I use? Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. null(java.lang.NullPointerException) . You need to benchmark. The null concept refers to the idea that a pointer can hold a special value that is not equal to another pointer. In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. Connect and share knowledge within a single location that is structured and easy to search. All content is copyright protected. Ah, gotcha. Thanks for contributing an answer to Stack Overflow! For example the following program doesn't compile. Connect and share knowledge within a single location that is structured and easy to search. Accessing or modifying a null object's field. Hi @Michael! To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. SonarLint IntelliJ 4.0.0.2916 Java Rule 'Null pointers should not be dereferenced' I'm getting this fault in the next code when obj can't be null in any scenario. 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). which would allow us to systematically observe what you are having. 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 . To subscribe to this RSS feed, copy and paste this URL into your RSS reader. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to bypass security measures. The 2nd NCCE/CS pair seems redundant with the first NCCE/CS pair. Sonar is ok. 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.. It does not point to any area of memory. At best, such an exception will cause abrupt program termination. Then we hit memcpy with length 0. Shouldn't the function check all pointers before dereferencing them or passing them to another function? Its purpose is to serve as a special value for a pointer that could indicate a special condition in your program. io.NotSerializableException : java. To learn more, see our tips on writing great answers. ncdu: What's going on with this second size column? Calls to extension methods are not reported because they can still operate on null values. That is, sets equivalent to a proper subset via an all-structure-preserving bijection. // <------- reported violation: NullPointerException might be thrown as 'bar' is nullable here, https://jira.sonarsource.com/browse/SONARJAVA-1490, https://groups.google.com/d/msgid/sonarqube/4752a999-246e-42c2-bbdc-8a44a5564ce9%40googlegroups.com. Carnegie Mellon University
When and how should I use a ThreadLocal variable? Mutually exclusive execution using std::atomic? And if there is no pointer_default declaration, then the default default is ref. 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). You're in a company-managed project. 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. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. What is pointed to should only be deleted if it was created with new. If malloc() fails, it returns a null pointer that is assigned to c_str. NullPointerException is a RuntimeException. I have a sonar alert on this call minRating.getRatgCaam(). Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. After that, you call res.getBody() again. What is a serialVersionUID and why should I use it? If you preorder a special airline meal (e.g. That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. If you write [ref], then a null pointer is not allowed, but if you write [unique], then a null pointer is permitted. When you have a variable of non-primitive type, it is a reference to an object. The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. 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. You can use Optional instead. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. And fwstr > is dereferenced in the following codes. 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. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. You can compare a pointer with NULL to test for the special condition. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Sonar false-positive on rule: Null pointers should not be dereferenced, Null Pointer Dereference issue not detected when the pointer is returned by another function. Please explain: Without this, we wont be able to help you. Avoid Returning null from Methods. Thanks for contributing an answer to Stack Overflow! A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. Issues Components. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow These can be: Invoking a method from a null object. extern char _etext; 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. IDE extension that lets you fix coding issues before they exist! 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. 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 Which version of SonarJava plugin do you have? Write a semantic patch to nd cases where the result of calling kmalloc is dereferenced with no previous NULL pointer test. Now (sonarqube java analyzer version 4.3.0.7717) it's supported and works fine. Styling contours by colour and by line thickness in QGIS. This likely means that youre on an ancient version of the Java analyzer. util.regex.Matcher, java - Swing .getParent() . Powered by Discourse, best viewed with JavaScript enabled. Instead use String.valueOf (object). Making statements based on opinion; back them up with references or personal experience. I suppose there is a question of "Is a pointer that points to 0 bytes valid?" Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. The alert is related to the sonar rule : Null pointers should not be dereferenced. Appropriate typecasting is necessary. The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. Cause we need throw our own Runtime Exception, well-known methods wont help. 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. Correct; a null pointer is not a valid pointer for the C library functions. How can this new ban on drag possibly be considered constitutional? Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. - the incident has nothing to do with me; can I use this this way? 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(). 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). Trying to understand how to get this basic Fourier Series. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. 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 */ What is generic pointer? That is why I explicitly check for this in my attempted solution. Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. 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. What is null pointer exception in android. rev2023.3.3.43278. 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. Made code more compliant with other rules. And the semantics, as I said, are different. C# static code analysis: Null pointers should not be dereferenced Products In-IDE IDE extension that lets you fix coding issues before they exist! Finally my method is returning a response with value of restTemplate. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? Much like dereferencing a dangling (or wild) pointer leads to undefined behavior, dereferencing a null pointer also leads to undefined behavior. 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. Im having trouble understanding your problem. 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 However, memory allocation > functions such as kstrdup() may fail and returns NULL. }. context.RaiseException , (/) It is useful to have a function with portable interface but platform-dependent implementation: extern bool invalid(const void *); The null pointer check for writing or dereferencing should be a compiler flag or library setting. Can I tell police to wait and call a lawyer when served with a search warrant? Software project. We can see that at obj.run(), obj can not be null, but is pointed out by Sonar. Identify where the allocation occurs. 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. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? That's true. EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. What are the effects of exceptions on performance in Java? public boolean isNameEmpty() { return getName().length() == 0; // Noncompliant; the result of getName() could be null, but isn't null-checked } . Here is our source code: Sign in to download full-size image 2008-2023 SonarSource S.A., Switzerland. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. I think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. There are many ways to resolve this. Null pointers should not be dereferenced. very old code or C code being worked into c++ may have functions that expect the user to delete the data. 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. sometimes FP occurs. Thus we should check > this kstrdup() operation. "After the incident", I started to be more careful not to trip over things. Should trycatch go inside or outside a loop? Dereferencing a null pointer is undefined behavior. Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. which version of SonarQube are you using? Additionally, if input_str is a null pointer, the call to strlen() dereferences a null pointer, also resulting in undefined behavior. Are there tables of wastage rates for different fruit and veg? Doing so will cause a NullReferenceException to be thrown. 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 can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). But no where in that particular idiom would a NULL pointer necessarily be deferenced. We really appreciate your help. 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. ii. Things go fine now. In multithreaded programs, null pointer dereferences can violate cache coherency policies and can cause resource leaks. What does "Could not find or load main class" mean? This compliant solution ensures that the pointer returned by png_malloc() is not null. int changed to size_t and if size_t parameter's is zero, allocate one word. Hi Andreas, Thanks for the feedback. Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. 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". ), 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). What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. 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. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? Essentially, this code and the previous dereference disagree as to whether this value is allowed to be null. I already tried to put ResponseEntity