I think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. The return value from strchr() is often NULL, but the dev might know that a specific strchr() function call will not return NULL. 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). 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). A reference to Nothing should never be dereferenced/accessed. Hello. The issue arises when dereferenced pointers are used. the Java one). 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. Phew, we're agreed here. We cannot understand how there could be a null pointer exception at the reported line. ii. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. Some Interesting Facts: 1) void pointers cannot be dereferenced. 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. Many platforms can support testing for those also. 1 Answer Sorted by: 2 Your code needs to do something about the possible NullPointerException when some exception is caught, because in this scenario the responseDto will be null. There is no guarantee that subsequent invocations are returning the same value, thats why issue is raised. Provide a self-contained reproducer (zipped project?) Small typo nit: "such as if i t pointed to freed memory" meant to say "if it" instead (removing whitespace). What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? [4] However, memory allocation > functions such as kstrdup() may fail and returns NULL. To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. . If not, this might be a bug. However there is no portable way to verify that the pointer is valid, other than checking for null. One could argue that all code examples would be redundant with the first pair. very old code or C code being worked into c++ may have functions that expect the user to delete the data. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? It does not point to any area of memory. Status: Dormant. This code also violates ERR33-C. Detect and handle standard library errors. 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. If copying takes place between objects that overlap, the behavior is undefined. Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, SonarQube - Null Pointer Dereference Issue. 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. Are there tables of wastage rates for different fruit and veg? Pointer members in structs are not checked. Whats the grammar of "For those whose stories they are"? Reports. When B is null, The control reaches inside the main if block only when length of A is 1. 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. It is useful to have a function with portable interface but platform-dependent implementation: extern bool invalid(const void *); Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? 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. With their flexibility, void pointers also bring some constraints. That is why I explicitly check for this in my attempted solution. 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 How can we prove that the supernatural or paranormal doesn't exist? 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?) Optimizers are optimizing based on this latitude and have been for years. util.regex.Matcher, java - Swing .getParent() . SonarQube - Null Pointer Dereference Issue java simonsirak (Simon Sirak) June 14, 2018, 1:18pm 1 Hi! which would allow us to systematically observe what you are having. , NPE : null-, . 3.7. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? ssize_t (*aio_read)(struct kiocb *, char __user *, size_t . Believing that dereferencing NULL shouldn't crash the system doesn't make it true. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? 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". Connect and share knowledge within a single location that is structured and easy to search. 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 . But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. . In C# and Java, all reference types can point to null. 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. 4. How can this new ban on drag possibly be considered constitutional? Accessing or modifying a null object's field. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. What is the point of Thrower's Bandolier? 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. Making statements based on opinion; back them up with references or personal experience. 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. Software project. 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. Appropriate typecasting is necessary. The method isNR(minRating) is a helper method that validate among other things, if the object minRating is null. Hi @Michael! IDE extension that lets you fix coding issues before they exist! The alert is related to the sonar rule : Null pointers should not be dereferenced. > Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to > the caller site. Much like dereferencing a dangling (or wild) pointer leads to undefined behavior, dereferencing a null pointer also leads to undefined behavior. SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. That is, sets equivalent to a proper subset via an all-structure-preserving bijection. And the semantics, as I said, are different. Does Counterspell prevent from any further spells being cast on a given turn? context.RaiseException . So the SIZE_MAX check was unnecessary. 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. I believe in this case, either expression would work. On many platforms, dereferencing a null pointer results inabnormal program termination, but this is not required by the standard. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. int changed to size_t and if size_t parameter's is zero, allocate one word. But even with this, the concerned object it tagged as a possible NullPointerException problem. 4500 Fifth Avenue Making statements based on opinion; back them up with references or personal experience. I say "theoretical" because I have not successfully produced strings of this length in testing. 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. Sonar is ok. Sonar can't determine that the helper method did the null validation. (C11, S7.24.2.1). 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. This will normally lead to an unhandled error, resulting in a segmentation fault. And fwstr > is dereferenced in the following codes. I suppose there is a question of "Is a pointer that points to 0 bytes valid?" (from res.getBody().getServiceResult() ). vegan) just to try it, does this inconvenience the caterers and staff? When and how should I use a ThreadLocal variable? can have the value zero on a call to that function. NULL vs Void Pointer - Null pointer is a value, while void pointer is a type. sonarLint (3.2.) 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 */ And the compliant solution guarantees that the pointer will be valid if the code calls memcpy(). Check whether a String is not Null and not Empty. Please explain: Without this, we wont be able to help you. Instead use String.valueOf (object). 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. All content is copyright protected. In the case of the ARM and XScale architectures, the 0x0 address is mapped in memory and serves as the exception vector table; consequently, dereferencing 0x0 did not cause an abnormal program termination. These can be: Invoking a method from a null object. SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. You're in a company-managed project. Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. 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 think you cover that in a different rule.) Issues Components. In some situations, however, dereferencing a null pointer can lead to the execution of arbitrary code [Jack 2007,van Sprundel 2006]. In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. Recovering from a blunder I made while emailing a professor. Trying to understand how to get this basic Fourier Series. 11 Sep, 2006. I've changed it to say null pointer instead of invalid pointer. Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. specifies the length of the array for a function. positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. If you try to access any member variables or methods with that variable, you are trying to dereference it. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. SonarJava Version 5.9.2 (build 16552). Now (sonarqube java analyzer version 4.3.0.7717) it's supported and works fine. NULL vs Uninitialized pointer - An uninitialized pointer stores an undefined value. Void pointers cannot be dereferenced as any other pointer. Essentially, this code and the previous dereference disagree as to whether this value is allowed to be null. // <------- 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. Reports. 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. ), 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. In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. Avoid Returning null from Methods. PS: I also tried the code in android studio which uses Lint and got no warnings. https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . The 2nd NCCE/CS pair seems redundant with the first NCCE/CS pair. Is there a single-word adjective for "having exceptionally strong moral principles"? Connect and share knowledge within a single location that is structured and easy to search. 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. It could be non-null the first time but not the second time, sonar does not know this. What is pointed to should only be deleted if it was created with new. 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). Trying to understand how to get this basic Fourier Series. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. - the incident has nothing to do with me; can I use this this way? But passing 0 to memcpy() is not one of them. Hi Andreas, Thanks for the feedback. How can we let this pass? 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. Pittsburgh, PA 15213-2612 Aaron:I suspect we are talking past each other. We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. assert(!invalid(p)); // or whatever, bool invalid(const void *p) { ncdu: What's going on with this second size column? The libpng library implements its own wrapper to malloc() that returns a null pointer on error or on being passed a 0-byte-length argument. The standard will simply copy 0 byteswhich is essentially a no-op. rev2023.3.3.43278. 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. But when length of A is 1, the control never reaches the else block. Is it possible to create a concave light? Cause we need throw our own Runtime Exception, well-known methods wont help. 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. A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. Doing so will cause a NullPointerException to be thrown. extern char _etext; The idea is not to guarantee validity, but to catch a substantial number of problems that could occur. And if there is no pointer_default declaration, then the default default is ref. "After the incident", I started to be more careful not to trip over things. Im very new to sonar, is there a way to add methods to the whitelist? A pointer to null (the 0 memory address) should never be dereferenced/accessed. When length is zero, it is probably unusable condition for this function. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. 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. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? null(java.lang.NullPointerException) . Thank you for clarifying your assertion until I understood it properly. It is still a pointer though, to use it you just have to cast it to another kind of pointer first. 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. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Im having trouble understanding your problem. Whoops, you're right. Powered by Discourse, best viewed with JavaScript enabled. I suggest that this topic needs to include calloc() and realloc() Refer to Linux man pages online for more enlightenment about malloc(), and friends. Is there a solution to add special characters from software and how to do it, Acidity of alcohols and basicity of amines. Should trycatch go inside or outside a loop? Asking for help, clarification, or responding to other answers. 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. 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.. Currently I'm working with SonarQube solving issues but I'm facing a trouble to how handle null pointers that shouldn't be dereferenced. We. res.getBody() == null || res.getBody().getServiceResult() == null). Asking for help, clarification, or responding to other answers. We resolved it by adding our tools path in the white list, and repackaging it. So no checking of the length is necessary (besides preventing integer overflow, which the compliant solution does). What is a NullPointerException, and how do I fix it?,What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them? 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. What does it mean that a reference must refer to an object, not a dereferenced null pointer? The issue is: memcpy() and friends do not explicitly state that a null pointer is a valid pointer value, even if the number of bytes to copy is 0. Is there a single-word adjective for "having exceptionally strong moral principles"? I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation.