null pointers should not be dereferenced

I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. I would also guess that pointers that point to the one-past-the-end of an array are also invalid. SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. After that, you call res.getBody() again. Just because something is a pointer does not mean you should call delete . The alert is related to the sonar rule : Null pointers should not be dereferenced. I suggest that this topic needs to include calloc() and realloc() Refer to Linux man pages online for more enlightenment about malloc(), and friends. Dereferencing a null pointer is undefined behavior, typically abnormal program termination. 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. , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow To learn more, see our tips on writing great answers. But when length of A is 1, the control never reaches the else block. 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. Java Specification Participation Agreement version in use: 2.0. 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. If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. 11 Sep, 2006. Does Counterspell prevent from any further spells being cast on a given turn? 3.Null pointers should not be derefer enced/accessed. in above code, (from res.getBody().getServiceResult() ). 1 Answer Sorted by: 1 Your code is ok. I added a comment to explain that SIZE_MAX is the limit of size_t. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? 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. 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". How can we let this pass? 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. Connect and share knowledge within a single location that is structured and easy to search. 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. Null pointers should not be dereferenced. Find centralized, trusted content and collaborate around the technologies you use most. Why is there a voltage on my HDMI and coaxial cables? vegan) just to try it, does this inconvenience the caterers and staff? Styling contours by colour and by line thickness in QGIS. Basically, yes. Can I tell police to wait and call a lawyer when served with a search warrant? (In contrast, the case of passing 0 bytes to malloc is addressed in C11.) 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). All content is copyright protected. SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. int changed to size_t and if size_t parameter's is zero, allocate one word. Not the answer you're looking for? 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. At this point we define size as strlen(input_str) + 1. When and how should I use a ThreadLocal variable? Is there a proper earth ground point in this switch box? If not, this might be a bug. 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. But even with this, the concerned object it tagged as a possible NullPointerException problem. Can you please start a new thread and be more explicit about the issue you are observing. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. This solution also ensures that theuser_data pointer is not null. I say "theoretical" because I have not successfully produced strings of this length in testing. Please direct comments on this JSR to the Spec Lead (s) Team. When a variable is declared as being a pointer to type void, it is known as a generic pointer. The only potential null is the return value of list(). Connect and share knowledge within a single location that is structured and easy to search. Pointer members in structs are not checked. Are there tables of wastage rates for different fruit and veg? Made code more compliant with other rules. Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. sonarLint (3.2.) Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. 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. Accessing or modifying a null object's field. Doing so will at best cause abrupt program termination, without the 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. Is it possible to create a concave light? Does it just mean failing to correctly check if a value is null? I guess you could write a proposal to modify the C Standard, but our coding standard is meant to provide guidance for the existing language. 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.) New replies are no longer allowed. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Why are physically impossible and logically impossible concepts considered separate in terms of probability? Asking for help, clarification, or responding to other answers. C# static code analysis: Null pointers should not be dereferenced Products In-IDE IDE extension that lets you fix coding issues before they exist! Shouldn't the function check all pointers before dereferencing them or passing them to another function? 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. 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. Null pointer should not be dereferenced , What are the effects of exceptions on performance in Java? Now (sonarqube java analyzer version 4.3.0.7717) it's supported and works fine. 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. attacker to bypass security measures. Share Improve this answer Follow answered Oct 5, 2017 at 16:27 , NPE : null-, . 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. 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. Could I capture, and I would be able to glean much security information from the dump? At We resolved it by adding our tools path in the white list, and repackaging it. Thanks for contributing an answer to Stack Overflow! This likely means that youre on an ancient version of the Java analyzer. JCP version in use: 2.6. In order to fix this, just do the following: BodyType body=res.getBody (); if (body == null || body.getServiceResult () == null) { return; } You can then even reuse body after that. What does "Could not find or load main class" mean? 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). If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? For example the following program doesn't compile. Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). If malloc() fails, it returns a null pointer that is assigned to c_str. Ticket opened : Thanks a lot for the minimalized reproducer ! sonarqube Seems the analizer don't recognice the logic with the funcional object Optional. NullPointerException is thrown when program attempts to use an object reference that has the null value. Void pointers cannot be dereferenced as any other pointer. It's a modular system with the . At worst, it could expose debugging information that would be useful to an attacker, or Is a PhD visitor considered as a visiting scholar? Which ensures that the chunkdata pointer is valid, but makes no such check to the user_data pointer. 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. I've changed it to say null pointer instead of invalid pointer. extern char _etext; Search for vulnerabilities resulting from the violation of this rule on the CERT website. The return value from strchr() is often NULL, but the dev might know that a specific strchr() function call will not return NULL. IMHO, the rule title should be changed to something less general. sometimes FP occurs. ncdu: What's going on with this second size column? 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. http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. I believe in this case, either expression would work. There are other problems with this code, as is noted in the rule. This sounds indeed like a bug in the flow when an exception is raised. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. Interactions/interfaces with C can't use references. 3.7. 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. Does a summoned creature play immediately after being summoned by a ready action? Software project. 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]. It also uses the unsigned type size_t to pass the length parameter, ensuring that negative values are not passed to func(). Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). Reports. void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. I have checked on multiple . > Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to > the caller site. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. }. The issue arises when dereferenced pointers are used. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to bypass security measures. 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. How do you ensure that a red herring doesn't violate Chekhov's gun? 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 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Sonar is ok. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. This rule applies to all null pointers, regardless of which function returned them. 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. io.NotSerializableException : java. Connect and share knowledge within a single location that is structured and easy to search. At best, such an exception will cause abrupt program termination. (C11, S7.24.2.1). Thanks, David! When and how should I use a ThreadLocal variable? 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. We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. 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. 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 All rights are expressly reserved. 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>. it could allow an attacker to bypass security measures. Is the God of a monotheism necessarily omnipotent? Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. validated for null in your method declaration with it: 2008-2023 SonarSource S.A., Switzerland. To learn more, see our tips on writing great answers. 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). It does not point to any area of memory. 2008-2023 SonarSource S.A., Switzerland. The method isNR(minRating) is a helper method that validate among other things, if the object minRating is null. Find centralized, trusted content and collaborate around the technologies you use most. Thanks for contributing an answer to Stack Overflow! Making statements based on opinion; back them up with references or personal experience. It looks like a logic bug, which can cause a memory leaking. The Clang Static Analyzer already has a checker to find the null pointer dereference in code, however it is not sufficient for higher abstractions such as C++ smart pointers or optionals. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. )}"); Explain about call by reference with an . PS: I also tried the code in android studio which uses Lint and got no warnings. 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.. sonarlint complains that ), Does not guess that return values from malloc(), strchr(), etc., can be NULL (The return value from malloc() is NULL only if there is OOMo and the dev might not care to handle that. Obviously the value of that pointer could have changed since the . We. 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. When c_str is dereferenced in memcpy(), the program exhibits undefined behavior. A reference to Nothing should never be dereferenced/accessed. best, such an exception will cause abrupt program termination. @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. The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. A NULL pointer can be dereferenced when signatures are being verified on PKCS7 signed or signedAndEnveloped data. Dereferencing a null pointer can lead to a denial of service. There are many ways to resolve this. This compliant solution eliminates the null pointer deference by initializing sk to tun->sk following the null pointer check. But passing 0 to memcpy() is not one of them. So the SIZE_MAX check was unnecessary. What is the point of Thrower's Bandolier? How do I align things in the following tabular environment? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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. A bug can cause them never to be reassigned. But what exactly does it mean to "dereference a null pointer"? Here is our source code: Sign in to download full-size image

Edmunds Elementary School Calendar, Prevue Hendryx Small Bird Cage, Tioga County, Pa Warrants, Adam Schiff Popularity Poll, Articles N