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SonarJava Version 5.9.2 (build 16552). We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. In my experience, there are reasons to check for a NULL pointer other than dereferencing it. This engine is validating execution paths and checking for non-null values or null-check along the way, exploring all the possibilities. It does not point to any area of memory. Is there a proper earth ground point in this switch box? 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. raiseException() return, Sonar Connect and share knowledge within a single location that is structured and easy to search. 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. sonarlint complains that It could be non-null the first time but not the second time, sonar does not know this. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? ), 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). Not the answer you're looking for? I added a comment to explain that SIZE_MAX is the limit of size_t. Is there a proper earth ground point in this switch box? How can I check before my flight that the cloud separation requirements in VFR flight rules are met? How can we let this pass? There are many ways to resolve this. It also uses the unsigned type size_t to pass the length parameter, ensuring that negative values are not passed to func(). Minimising the environmental effects of my dyson brain. 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. Do "superinfinite" sets exist? Off by one error: It is the third example. In the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. SonarQube Version 6.7.2 (build 37468) 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. positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. sonarqube That makes sense. The n=0 is a mildly interesting edge case: Clearly a pointer that points to at least one valid byte could be used as the src or dest pointer to a call to memcpy(, 0). In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. 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. If malloc() fails, it returns a null pointer that is assigned to c_str. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). How can we prove that the supernatural or paranormal doesn't exist? You can use Optional instead. in above code, Alternate Terms Relationships 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. 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. This sounds indeed like a bug in the flow when an exception is raised. Is the God of a monotheism necessarily omnipotent? 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. 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. Dereferencing a null pointer results in undefined behavior. minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). If you try to access any member variables or methods with that variable, you are trying to dereference it. Carnegie Mellon University Find centralized, trusted content and collaborate around the technologies you use most. Now (sonarqube java analyzer version 4.3.0.7717) it's supported and works fine. 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. . // <------- 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. Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, SonarQube - Null Pointer Dereference Issue. EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. vegan) just to try it, does this inconvenience the caterers and staff? 4. You're in a company-managed project. But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. So the SIZE_MAX check was unnecessary. java Things go fine now. 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). 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 You need to benchmark. Can you please start a new thread and be more explicit about the issue you are observing. How do I align things in the following tabular environment? res.getBody() == null || res.getBody().getServiceResult() == null). Is it possible to create a concave light? How to deal with "java.lang.OutOfMemoryError: Java heap space" error? Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. I have checked on multiple . Find centralized, trusted content and collaborate around the technologies you use most. sonar-java. 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. That is why I explicitly check for this in my attempted solution. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? The method isNR(minRating) is a helper method that validate among other things, if the object minRating is null. I don't need to do this validation again. . that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). I suppose we can check that that is not null, but we cannot check that it is valid (in any portable way). Which @NotNull Java annotation should I use? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Are there tables of wastage rates for different fruit and veg? A reference to Nothing should never be dereferenced/accessed. return p == NULL || (char *)p < &_etext; 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). We can not disable any rule, sonar do validation in "Sonar way" (actual name of profile :) ), so we will need to mark them "Wont fix" each time it appear again in new code. . 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. Aaron:I suspect we are talking past each other. And the semantics, as I said, are different. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. In the code, we check the not nullity with java.util.Objects.nonNull(). We. Explain about call by reference with an . Dereferencing > this null pointer may cause the kernel go wrong. Void pointers cannot be dereferenced as any other pointer. validated for null in your method declaration with it: 2008-2023 SonarSource S.A., Switzerland. 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 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(). Java Specification Participation Agreement version in use: 2.0. Powered by Discourse, best viewed with JavaScript enabled. 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 . 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. I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. 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. Null pointer should not be dereferenced , 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. There are other problems with this code, as is noted in the rule. If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? Automated Detection Null pointer dereferences can happen in path-dependent ways. specifies the length of the array for a function. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, SonarQube null pointers should not be dereferenced on try/catch, How Intuit democratizes AI development across teams through reusability. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. This is a feature that we are currently heavily working on to be able to switch off such kind of false positives. The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. This issues is displayed by SonarQube. Sonar is ok. Asking for help, clarification, or responding to other answers. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. At worst, it could expose debugging information that would be useful to an attacker or it could allow an , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow This solution also ensures that theuser_data pointer is not null. When and how should I use a ThreadLocal variable? 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. Trying to understand how to get this basic Fourier Series. (/). Finally, there is the matter of the compliant solution. Is there a single-word adjective for "having exceptionally strong moral principles"? util.regex.Matcher, java - Swing .getParent() . Is null check needed before calling instanceof? positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". Cause we need throw our own Runtime Exception, well-known methods wont help. 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. Batch split images vertically in half, sequentially numbering the output files, Recovering from a blunder I made while emailing a professor. When you have a variable of non-primitive type, it is a reference to an object. Search for vulnerabilities resulting from the violation of this rule on the CERT website. Whoops, you're right. Just a few words about the rule now. How can we prove that the supernatural or paranormal doesn't exist? A pointer to null (the 0 memory address) should never be dereferenced/accessed. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Making statements based on opinion; back them up with references or personal experience. 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>. C# static code analysis: Null pointers should not be dereferenced Products In-IDE IDE extension that lets you fix coding issues before they exist! 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. 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. Two null pointers will always be equal to each other. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? 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. The return value from strchr() is often NULL, but the dev might know that a specific strchr() function call will not return NULL. Identify where the allocation occurs. 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. 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". SonarJava. Im very new to sonar, is there a way to add methods to the whitelist? 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! When B is null, The control reaches inside the main if block only when length of A is 1. I'd guess WG14 has considered these questions, but I haven't until now :). Making statements based on opinion; back them up with references or personal experience. 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). In multithreaded programs, null pointer dereferences can violate cache coherency policies and can cause resource leaks. SonarQube null pointers should not be dereferenced on try/catch, Sonarcube :Null pointers should not be dereferenced, How do you get out of a corner when plotting yourself into a corner. So we have to check all the arguments before performing any actions. That interpretation of the standard is not supported universally. Im having trouble understanding your problem. In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. Is the God of a monotheism necessarily omnipotent? This compliant solution eliminates the null pointer deference by initializing sk to tun->sk following the null pointer check. Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. 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. The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. Which version of SonarJava plugin do you have? Unfortunately, its actual state also has some limitations, like the one you are hitting here. Likewise, pointers to freed memory are not valid. That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. Status: Dormant. Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. 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. We cannot understand how there could be a null pointer exception at the reported line. This is a matter of style, and also following code walkthrough. Mutually exclusive execution using std::atomic? 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. 11 Sep, 2006. Now, you can find the list of whitelisted methods here. Using Kolmogorov complexity to measure difficulty of problems? 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. Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. 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.. The issue arises when dereferenced pointers are used. Why is there a voltage on my HDMI and coaxial cables? Note that it doesn't know how to check for non-heap, non-stack. Put a new ResponseEntity is wrong because I won't know what will be the answer for the status of http. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. {"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. The fact that you can't pass a null (no object) with a reference parameter can be a reason to use a pointer instead. Asking for help, clarification, or responding to other answers. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. Styling contours by colour and by line thickness in QGIS. IDE extension that lets you fix coding issues before they exist! How to use Slater Type Orbitals as a basis functions in matrix method correctly? which would allow us to systematically observe what you are having. Powered by Discourse, best viewed with JavaScript enabled. If you preorder a special airline meal (e.g. Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. How can this new ban on drag possibly be considered constitutional? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. I'd guess null pointers are not valid, even though they point to 0 bytes. This code also violates ERR33-C. Detect and handle standard library errors. Additionally, if input_str is a null pointer, the call to strlen() dereferences a null pointer, also resulting in undefined behavior. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Obviously the value of that pointer could have changed since the . }. 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. You can compare a pointer with NULL to test for the special condition. Connect and share knowledge within a single location that is structured and easy to search. Also, the term 'pointer' is bad (but maybe it comes from the FindBugs tool): Java doesn't have pointers, it has references. The final NCCE is actually more insidious than it seems at first. Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). 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 think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? But even with this, the concerned object it tagged as a possible NullPointerException problem. Not the answer you're looking for? What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Is there a single-word adjective for "having exceptionally strong moral principles"? - the incident has nothing to do with me; can I use this this way? ability to run any cleanup processes. very old code or C code being worked into c++ may have functions that expect the user to delete the data. 2008-2023 SonarSource S.A., Switzerland. Thanks, David! 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). 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. Is there a proper earth ground point in this switch box? What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? 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. 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. Does it just mean failing to correctly check if a value is null? This topic was automatically closed 7 days after the last reply. In C, dereferencing a null pointer is undefined behavior. Good question! NULL vs Uninitialized pointer - An uninitialized pointer stores an undefined value. Passing ownership of something also requires pointers. attacker to bypass security measures. However, memory allocation > functions such as kstrdup() may fail and returns NULL. This is indeed an obvious False Positive from the rule. ncdu: What's going on with this second size column? Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. the Java one). And if there is no pointer_default declaration, then the default default is ref. 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. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? Hi Andreas, Thanks for the feedback. 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). (C11, S7.24.2.1). Thanks for the feedback. A bug can cause them never to be reassigned. Finally my method is returning a response with value of restTemplate. 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 . Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. Issues Components. Shouldn't the function check all pointers before dereferencing them or passing them to another function? 412-268-5800, 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 pointer. Im currently using SonarQube version 5.6.6. better way to handle this is to store the result of method invocation in a variable. 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} Key here (explains table format and definitions), EXP34-C = Union( CWE-690, list) where list =. Can I tell police to wait and call a lawyer when served with a search warrant? You're in a company-managed project. Recovering from a blunder I made while emailing a professor. static-code-analysis Why does the second compliant example permit using possibly-null pointers? SonarQube - Null Pointer Dereference Issue java simonsirak (Simon Sirak) June 14, 2018, 1:18pm 1 Hi! SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. @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. For example the following program doesn't compile. 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 */ In Java, a special null value can be assigned to an object reference.