There are many ways to resolve this. Finally, there is the matter of the compliant solution. 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. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. You need to benchmark. There is no guarantee that subsequent invocations are returning the same value, thats why issue is raised. (/). 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. If malloc() fails, it returns a null pointer that is assigned to c_str. 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 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). Reference vs dereference pointers in arguments C++/C All content is copyright protected. 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. 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. Null pointers should not be dereferenced (#42) Issues - GitLab 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>. 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. 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. {"serverDuration": 214, "requestCorrelationId": "084acdc104f21c51"}, EXP34-C. Do not dereference null pointers, Clever Attack Exploits Fully-Patched Linux Kernel, ERR33-C. Detect and handle standard library errors, one compliant and one non-compliant example, CERT Oracle Secure Coding Standard for Java, EXP01-J. Is there a proper earth ground point in this switch box? Calls to extension methods are not reported because they can still operate on null values. By explicitly teaching the C++ standard class behaviors we can make the Analyzer to find more bugs related to modern C++ code. Find centralized, trusted content and collaborate around the technologies you use most. What is a NullPointerException, and how do I fix it? The issue arises when dereferenced pointers are used. Good question! 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]. 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. How to get rid of NullPointerException - freeCodeCamp.org Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). 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. void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. Making statements based on opinion; back them up with references or personal experience. 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. This engine is validating execution paths and checking for non-null values or null-check along the way, exploring all the possibilities. A bug can cause them never to be reassigned. Thanks for your relpy. Dereferencing a null pointer results in undefined behavior. 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. This topic was automatically closed 7 days after the last reply. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. Hi Andreas, Thanks for the feedback. You can compare a pointer with NULL to test for the special condition. , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow Finally my method is returning a response with value of restTemplate. A pointer to null (the 0 memory address) should never be dereferenced/accessed. sonarlint complains that sonarlint, sonarLint (3.2.) 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. 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. Why does Mister Mxyzptlk need to have a weakness in the comics? This is a feature that we are currently heavily working on to be able to switch off such kind of false positives. . Alternate Terms Relationships By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Connect and share knowledge within a single location that is structured and easy to search. It's a modular system with the . Issues Components. Phew, we're agreed here. Is the God of a monotheism necessarily omnipotent? 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). Making statements based on opinion; back them up with references or personal experience. The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. Thanks for contributing an answer to Stack Overflow! Can you please start a new thread and be more explicit about the issue you are observing. 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! Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. By 'valid pointers' I mean that both src and dest pointers are not null and they both point to non-overlapping arrays containing at least n bytes each. If you call connect() function, it better do the connection, but failing simply because some ptr is NULL is not good behaviour -- failures should . Trying to understand how to get this basic Fourier Series. Thank you for clarifying your assertion until I understood it properly. A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). Powered by Discourse, best viewed with JavaScript enabled. This code also violates ERR33-C. Detect and handle standard library errors. Now (sonarqube java analyzer version 4.3.0.7717) it's supported and works fine. How to deal with "java.lang.OutOfMemoryError: Java heap space" error? That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. This compliant solution ensures that both input_str andthe pointer returned by malloc() are not null: This noncompliant code example is from a version of drivers/net/tun.c and affects Linux kernel 2.6.30 [Goodin 2009]: The sk pointer is initialized to tun->sk before checking if tun is a null pointer. which would allow us to systematically observe what you are having. Mutually exclusive execution using std::atomic? Which @NotNull Java annotation should I use? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. Pittsburgh, PA 15213-2612 Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. So you can declare a string t and then add characters to the string with a plus sign : t += 'a'; The code you are having issue with is just moving the pointer to the next character which the foreach is already doing. Could I capture, and I would be able to glean much security information from the dump? 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. The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). 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 */ I think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. Find centralized, trusted content and collaborate around the technologies you use most. Automated Detection Null pointer dereferences can happen in path-dependent ways. Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. 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. [RSPEC-2259] - Jira I added an assertion to that compliant code example. 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. Is there a single-word adjective for "having exceptionally strong moral principles"? Essentially, this code and the previous dereference disagree as to whether this value is allowed to be null. As a result, this noncompliant code example is vulnerable to a null pointer dereference exploit, because null pointer dereferencing can be permitted on several platforms, for example, by using mmap(2) with the MAP_FIXED flag on Linux and Mac OS X, or by using the shmat() POSIX function with the SHM_RND flag [Liu 2009]. Pointer is so confusing : Stack with singly linked list in C - Stack What is null pointer exception in android. best, such an exception will cause abrupt program termination. Status: Dormant. This rule applies to all null pointers, regardless of which function returned them. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. Thanks for contributing an answer to Stack Overflow! java - sonarLint "Null pointers should not be that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. On many platforms, dereferencing a null pointer results in abnormal program termination, but this is not required by the standard. 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. Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. // <------- 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. 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). How to avoid dereferencing null pointers in Java - Quora A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. New replies are no longer allowed. We cannot understand how there could be a null pointer exception at the reported line. For the time being, I would unfortunately recommend to mark as False Positive the issue. Identify where the allocation occurs. I would also guess that pointers that point to the one-past-the-end of an array are also invalid. Optimizers are optimizing based on this latitude and have been for years. This issues is displayed by SonarQube. http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. 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 . 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've changed it to say null pointer instead of invalid pointer. Can I tell police to wait and call a lawyer when served with a search warrant? 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. Trying to understand how to get this basic Fourier Series. Its purpose is to serve as a special value for a pointer that could indicate a special condition in your program. rev2023.3.3.43278. PS: I also tried the code in android studio which uses Lint and got no warnings. Thanks for the feedback. How to tell which packages are held back due to phased updates. 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. So we have to check all the arguments before performing any actions. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. 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?) 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. There are many ways to resolve this. There is a missing check for the return value from . Recovering from a blunder I made while emailing a professor. Please direct comments on this JSR to the Spec Lead (s) Team. You're in a company-managed project. ", 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".