null pointers should not be dereferenced

isEmpty(Collection collection) Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. 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. Sonar is ok. What does it mean that a reference must refer to an object, not a dereferenced null pointer? What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. Goal Which @NotNull Java annotation should I use? Appropriate typecasting is necessary. Rule squid:S2259 is based on a Symbolic Execution (SE) engine. On many platforms, dereferencing a null pointer results inabnormal program termination, but this is not required by the standard. That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. Is it possible to create a concave light? 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. which version of SonarQube are you using? 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. Passing ownership of something also requires pointers. At worst, it could expose debugging information that would be useful to an attacker, or It's a modular system with the . For the time being, I would unfortunately recommend to mark as False Positive the issue. void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Alternate Terms Relationships // <------- 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. To learn more, see our tips on writing great answers. Using platform-specific means (e.g. 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 (?,?,?,?,?,?,?,? There is no guarantee that subsequent invocations are returning the same value, thats why issue is raised. Which ensures that the chunkdata pointer is valid, but makes no such check to the user_data pointer. This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. And the semantics, as I said, are different. It could be non-null the first time but not the second time, sonar does not know this. 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. SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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). It also uses the unsigned type size_t to pass the length parameter, ensuring that negative values are not passed to func(). Correct; a null pointer is not a valid pointer for the C library functions. If not, this might be a bug. 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. Find centralized, trusted content and collaborate around the technologies you use most. 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. To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. Share Improve this answer Follow answered Oct 5, 2017 at 16:27 Identify where the allocation occurs. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? If you write [ref], then a null pointer is not allowed, but if you write [unique], then a null pointer is permitted. (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). 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]. EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. So no checking of the length is necessary (besides preventing integer overflow, which the compliant solution does). Why do academics stay as adjuncts for years rather than move around? What sort of strategies would a medieval military use against a fantasy giant? I have a sonar alert on this call minRating.getRatgCaam(). If you preorder a special airline meal (e.g. Much like dereferencing a dangling (or wild) pointer leads to undefined behavior, dereferencing a null pointer also leads to undefined behavior. How do I align things in the following tabular environment? Now (sonarqube java analyzer version 4.3.0.7717) it's supported and works fine. 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. 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 Finally, there is the matter of the compliant solution. Why does the second compliant example permit using possibly-null pointers? 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. Ticket opened : Thanks a lot for the minimalized reproducer ! SonarJava. It could be non-null the first time but not the second time, sonar does not know this. Null pointers should not be dereferenced. > Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to > the caller site. minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). Not the answer you're looking for? Why does Mister Mxyzptlk need to have a weakness in the comics? I suggest that this topic needs to include calloc() and realloc() Refer to Linux man pages online for more enlightenment about malloc(), and friends. My question is; is my solution incorrect? Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. 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. 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. ability to run any cleanup processes. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. Does it just mean failing to correctly check if a value is null? SonarQube - Null Pointer Dereference Issue java simonsirak (Simon Sirak) June 14, 2018, 1:18pm 1 Hi! context.RaiseException , (/) When I added the not null validation as sonar suggest. Connect and share knowledge within a single location that is structured and easy to search. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. . You can use Optional instead. 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. 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. 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. Dereferencing a null pointer is undefined behavior, typically abnormal program termination. Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, S2259: Null pointers should not be dereferenced, find the list of whitelisted methods here, Rule java:S2259: False-positive NullPointerException bug logged when variable is null-checked by an imported method, What is the issue you are observing, in details, What version of SonarSource products you are using, as well as the version of SonarJava. Styling contours by colour and by line thickness in QGIS. Also, the term 'pointer' is bad (but maybe it comes from the FindBugs tool): Java doesn't have pointers, it has references. Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. How do I align things in the following tabular environment? C# static code analysis: Null pointers should not be dereferenced Products In-IDE IDE extension that lets you fix coding issues before they exist! This will normally lead to an unhandled error, resulting in a segmentation fault. 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>. 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. Off by one error: It is the third example. However there is no portable way to verify that the pointer is valid, other than checking for null. Is there a proper earth ground point in this switch box? How handle the initialization of "responseDto" without "null" because is throwing the issue on sonar. The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. context.RaiseException . Is there a proper earth ground point in this switch box? The user_data pointer could be invalid in other ways, such as pointing to freed memory. 2008-2023 SonarSource S.A., Switzerland. Hi Andreas, Thanks for the feedback. As for today, the SE engine is able to explore non-overridable methods (static, for instance), when declared in the same file being analyzed. The above check can't hurt, as I guess you could have a system with a 32-bit size_t that had a ton of memory and had some crazy banking/selector scheme with pointers. name result . What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. You're in a company-managed project. How can this new ban on drag possibly be considered constitutional? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Dereferencing a null pointer results in undefined behavior. My below code where I'm calling a stored procedure is giving a null pointer exception. This sounds indeed like a bug in the flow when an exception is raised. At Phew, we're agreed here. An awesome tip to avoid NPE is to return empty strings or empty collections rather than null. Please direct comments on this JSR to the Spec Lead (s) Team. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. sometimes FP occurs. 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. The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. Thank you for clarifying your assertion until I understood it properly. You can use Optional instead. The return value from strchr() is often NULL, but the dev might know that a specific strchr() function call will not return NULL. Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? 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. Carnegie Mellon University Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, SonarQube - Null Pointer Dereference Issue. 1 Answer Sorted by: 1 Your code is ok. Software project. Is there a single-word adjective for "having exceptionally strong moral principles"? 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Seems the analizer don't recognice the logic with the funcional object Optional. Trying to understand how to get this basic Fourier Series. res.getBody() == null || res.getBody().getServiceResult() == null). }. There is a missing check for the return value from . The issue arises when dereferenced pointers are used. It also adds assertions to document that certain other pointers must not be null. Could I capture, and I would be able to glean much security information from the dump? I think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. 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. In my experience, there are reasons to check for a NULL pointer other than dereferencing it. Is it possible to create a concave light? So the SIZE_MAX check was unnecessary. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. io.NotSerializableException : java. Thanks for contributing an answer to Stack Overflow! 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]. The result of calling such a helper function should be . ncdu: What's going on with this second size column? Likewise, pointers to freed memory are not valid. Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). Your assertion is not backed by the wording in the standard, nor by common implementer understanding. You're in a company-managed project. very old code or C code being worked into c++ may have functions that expect the user to delete the data. specifies the length of the array for a function. Should trycatch go inside or outside a loop? At best, such an exception will cause abrupt program termination. Does Java have support for multiline strings? In multithreaded programs, null pointer dereferences can violate cache coherency policies and can cause resource leaks. But when length of A is 1, the control never reaches the else block. Are there tables of wastage rates for different fruit and veg? If malloc() fails, it returns a null pointer that is assigned to c_str. Check whether a String is not Null and not Empty. Whoops, you're right. I don't need to do this validation again. 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. This issues is displayed by SonarQube. To learn more, see our tips on writing great answers. This code also violates ERR33-C. Detect and handle standard library errors. We can see that at obj.run(), obj can not be null, but is pointed out by Sonar. As for copy vs pointer/reference - it depends. The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). The correct idiom is to only allocate storage if the pointer is currently NULL. Trying to understand how to get this basic Fourier Series. Write a semantic patch to nd cases where the result of calling kmalloc is dereferenced with no previous NULL pointer test. There are other problems with this code, as is noted in the rule. The null pointer check for writing or dereferencing should be a compiler flag or library setting. Find centralized, trusted content and collaborate around the technologies you use most. isEmpty(Map map) Thanks for contributing an answer to Stack Overflow! Issues Components. 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. Hello. The fact that you can't pass a null (no object) with a reference parameter can be a reason to use a pointer instead. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Sonar: Null pointers should not be dereferenced, Why should Java 8's Optional not be used in arguments, Sonar alert : "private" methods that don't access instance data should be "static", sonarLint complains "Null pointers should not be dereferenced (squid:S2259)" despite that possibility being handled, Java: (false?) Sonar is ok. Sonar can't determine that the helper method did the null validation. Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. Making statements based on opinion; back them up with references or personal experience. 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. 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. 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. , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow What is a serialVersionUID and why should I use it? 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). Currently I'm working with SonarQube solving issues but I'm facing a trouble to how handle null pointers that shouldn't be dereferenced. 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. Avoid Returning null from Methods. Do "superinfinite" sets exist? The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. Powered by Discourse, best viewed with JavaScript enabled. I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. But what exactly does it mean to "dereference a null pointer"? Doing so will at best cause abrupt program termination, without the rev2023.3.3.43278. . 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.

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