Many platforms can support testing for those also. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. In my experience, there are reasons to check for a NULL pointer other than dereferencing it. . . This rule applies to all null pointers, regardless of which function returned them. With their flexibility, void pointers also bring some constraints. C static code analysis: Null pointers should not be dereferenced C static code analysis Unique rules to find Bugs, Vulnerabilities, Security Hotspots, and Code Smells in your C code All rules 311 Vulnerability 13 Bug 74 Security Hotspot 18 Code Smell 206 Quick Fix 14 Tags "memset" should not be used to delete sensitive data Vulnerability Does Java have support for multiline strings? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Software project. Recovering from a blunder I made while emailing a professor. Some Interesting Facts: 1) void pointers cannot be dereferenced. Im having trouble understanding your problem. CWE - CWE-476: NULL Pointer Dereference (4.10) - Mitre Corporation static-code-analysis can have the value zero on a call to that function. And the compliant solution guarantees that the pointer will be valid if the code calls memcpy(). By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Just a few words about the rule now. This sounds indeed like a bug in the flow when an exception is raised. How to deal with "java.lang.OutOfMemoryError: Java heap space" error? How to use Slater Type Orbitals as a basis functions in matrix method correctly? [4] 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. Description: This JSR will work to develop standard annotations (such as @NonNull) that can be applied to Java programs to assist tools that detect software defects. However, memory allocation > functions such as kstrdup() may fail and returns NULL. Recovering from a blunder I made while emailing a professor. Shouldn't the function check all pointers before dereferencing them or passing them to another function? Dereferencing a null pointer is undefined behavior, typically abnormal program termination. , . The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. How to fix int cannot be dereferenced? Explained by Sharing Culture 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. 4. https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx Aaron:I suspect we are talking past each other. Java Specification Participation Agreement version in use: 2.0. All content is copyright protected. That interpretation of the standard is not supported universally. ), 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. NULL vs Void Pointer - Null pointer is a value, while void pointer is a type. 2008-2023 SonarSource S.A., Switzerland. 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. When and how should I use a ThreadLocal variable? The test was added to catch the possibly theoretical situation where the length of input_str was somehow the maximum size for size_t, and adding one to this size in the malloc expression (to allocated space for the trailing null byte) results in an integer overflow. A reference to null should never be dereferenced/accessed. Making statements based on opinion; back them up with references or personal experience. sonarlint complains that Made code more compliant with other rules. At best, such an exception will cause abrupt program termination. 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. In some situations, however, dereferencing a null pointer can lead to the execution of arbitrary code [Jack 2007,van Sprundel 2006]. 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. There are many ways to resolve this. IMHO, the rule title should be changed to something less general. At Doing so will cause a NullPointerException to be thrown. U1 merged - It is a great text book for learning about linux devices. S2259: Null pointers should not be dereferenced - Sonar Community attacker to bypass security measures. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. I already tried to put ResponseEntity responseDto inside my try clause assigning and returning the respective value but its mandatory to return something out the try/catch. Dereferencing a null pointer results in undefined behavior. Since you cannot have a variable of type void, the pointer will not point to any data and therefore cannot be dereferenced. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. NULL vs Uninitialized pointer - An uninitialized pointer stores an undefined value. When should pointers be checked for NULL in C? This is a feature that we are currently heavily working on to be able to switch off such kind of false positives. 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. When length is zero, it is probably unusable condition for this function. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. Please explain: Without this, we wont be able to help you. specifies the length of the array for a function. Making statements based on opinion; back them up with references or personal experience. Share Improve this answer Follow answered Oct 5, 2017 at 16:27 Find centralized, trusted content and collaborate around the technologies you use most. Sonar is ok. 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. // <------- 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. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. Dereferencing > this null pointer may cause the kernel go wrong. Does a summoned creature play immediately after being summoned by a ready action? IDE extension that lets you fix coding issues before they exist! This is a matter of style, and also following code walkthrough. Reports. Null Pointer Exception In Java - GeeksforGeeks - A computer science A reference to null should never be dereferenced/accessed. 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. (/). Mutually exclusive execution using std::atomic? A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). You're in a company-managed project. sonarLint (3.2.) Pointer Arithmetic in c - Unit - 4 1. Define pointer. Explain about the This code also violates ERR33-C. Detect and handle standard library errors. I'd guess null pointers are not valid, even though they point to 0 bytes. If not, this might be a bug. Unfortunately, its actual state also has some limitations, like the one you are hitting here. 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. The problem is that something like %*pbl which reads a bitmask, will save the pointer to the bitmask in the buffer. 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. It also reinforces the notion to the reader that any time you see arithmetic in an allocation expression, you need to think about corner-cases. Now, you can find the list of whitelisted methods here. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? strongSwan - strongSwan Vulnerability (CVE-2023-26463) () 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. Two null pointers will always be equal to each other. 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). rev2023.3.3.43278. 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" Find centralized, trusted content and collaborate around the technologies you use most. Passing ownership of something also requires pointers. Hi @Michael! False fault 'Null pointers should not be dereferenced' using Optional 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. Fix S2583/S2589 FP: On null check if instance is used in try block - GitHub Powered by Discourse, best viewed with JavaScript enabled. name result . Using Kolmogorov complexity to measure difficulty of problems? context.RaiseException , (/) , NPE : null-, . 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 It is still a pointer though, to use it you just have to cast it to another kind of pointer first. Alternate Terms Relationships New replies are no longer allowed. Should trycatch go inside or outside a loop? These can be: Invoking a method from a null object. [PATCH] drm_edid-load: Fix a missing-check bug in drivers/gpu/drm/drm 4500 Fifth Avenue However there is no portable way to verify that the pointer is valid, other than checking for null. How can we prove that the supernatural or paranormal doesn't exist? I reordered that code example to do all the checks before allocations. NullPointerException is thrown when program attempts to use an object reference that has the null value. http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. On many platforms, dereferencing a null pointer results in abnormal program termination, but this is not required by the standard. JCP version in use: 2.6. In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. 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. If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. 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. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. 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. You need to benchmark. 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. To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. A bug can cause them never to be reassigned. All rights are expressly reserved. On such a call, a function that locates a character finds no occurrence, a function that compares two character sequences returns zero, and a function that copies characters copies zero characters. On such a call, a function that locates a character finds no occurrence, a function that compares two character sequences returns zero, and a function that copies characters copies zero characters. EXP01-J. Do not use a null in a case where an object is required Asking for help, clarification, or responding to other answers. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? OpenSSL Releases Security Update - NHS Digital Appropriate typecasting is necessary. Find centralized, trusted content and collaborate around the technologies you use most. Connect and share knowledge within a single location that is structured and easy to search. SonarJava Version 5.9.2 (build 16552). 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. Obviously the value of that pointer could have changed since the . isEmpty(Collection collection) The fact that you can't pass a null (no object) with a reference parameter can be a reason to use a pointer instead. SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. Believing that dereferencing NULL shouldn't crash the system doesn't make it true. Your assertion is not backed by the wording in the standard, nor by common implementer understanding. 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. 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. 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(). Cause we need throw our own Runtime Exception, well-known methods wont help. . Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. You're in a company-managed project. The user_data pointer could be invalid in other ways, such as pointing to freed memory. sonarlint, sonarLint (3.2.) My below code where I'm calling a stored procedure is giving a null pointer exception. IDE extension that lets you fix coding issues before they exist! But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. Can you please start a new thread and be more explicit about the issue you are observing. Thanks for contributing an answer to Stack Overflow! I suggest that this topic needs to include calloc() and realloc() Refer to Linux man pages online for more enlightenment about malloc(), and friends. 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. This issues is displayed by SonarQube. 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). I have a sonar alert on this call minRating.getRatgCaam(). which would allow us to systematically observe what you are having. 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. I believe in this case, either expression would work. As for copy vs pointer/reference - it depends. [PATCH v2] vsprintf: Do not have bprintf dereference pointers By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Connect and share knowledge within a single location that is structured and easy to search. )}"); Analysis of Haiku Operating System (BeOS Family) by PVS-Studio. Part 1 io.NotSerializableException : java. 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 . 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. 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. VB.NET static code analysis: Null pointers should not be dereferenced