null pointers should not be dereferenced

The standard will simply copy 0 byteswhich is essentially a no-op. io.NotSerializableException : java. If malloc() fails, it returns a null pointer that is assigned to c_str. Powered by Discourse, best viewed with JavaScript enabled. 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. Asking for help, clarification, or responding to other answers. Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). If you call connect() function, it better do the connection, but failing simply because some ptr is NULL is not good behaviour -- failures should . Interactions/interfaces with C can't use references. 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. Null Pointers - Keil forum - Support forums - Arm Community The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? specifies the length of the array for a function. (from res.getBody().getServiceResult() ). Im currently using SonarQube version 5.6.6. better way to handle this is to store the result of method invocation in a variable. sometimes FP occurs. 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. PDF Fourth Coccinelle Workshop { Exercises And the semantics, as I said, are different. The result of calling such a helper function should be . ), 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). Is the God of a monotheism necessarily omnipotent? In Java, a special null value can be assigned to an object reference. The final NCCE is actually more insidious than it seems at first. Analysis of Haiku Operating System (BeOS Family) by PVS-Studio. Part 1 The alert is related to the sonar rule : Null pointers should not be dereferenced. Sonar violation: Null pointers should not be dereferenced #7459 - GitHub Can I tell police to wait and call a lawyer when served with a search warrant? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Sonar is ok. Sonar can't determine that the helper method did the null validation. In the code, we check the not nullity with java.util.Objects.nonNull(). 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. SonarJava Version 5.9.2 (build 16552). Why does Mister Mxyzptlk need to have a weakness in the comics? - the incident has nothing to do with me; can I use this this way? rev2023.3.3.43278. 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. This rule applies to all null pointers, regardless of which function returned them. Sonar: Null pointers should not be dereferenced - Stack Overflow 9.7 Null pointers - Learn C++ - LearnCpp.com IDE extension that lets you fix coding issues before they exist! 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. 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. PS: I also tried the code in android studio which uses Lint and got no warnings. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. Which version of SonarJava plugin do you have? Reports. At worst, it could expose debugging information that would be useful to an attacker, or On many platforms, dereferencing a null pointer results in abnormal program termination, but this is not required by the standard. java - sonarLint "Null pointers should not be int changed to size_t and if size_t parameter's is zero, allocate one word. Your assertion is not backed by the wording in the standard, nor by common implementer understanding. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? However there is no portable way to verify that the pointer is valid, other than checking for null. 4. Null pointers should not be dereferenced (#42) Issues - GitLab This code also violates ERR33-C. Detect and handle standard library errors. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. public boolean isNameEmpty() { return getName().length() == 0; // Noncompliant; the result of getName() could be null, but isn't null-checked } . 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). This is a matter of style, and also following code walkthrough. A reference to Nothing should never be dereferenced/accessed. When should pointers be checked for NULL in C? Does it just mean failing to correctly check if a value is null? 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. 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. 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! 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 . Is it possible to rotate a window 90 degrees if it has the same length and width? A NULL pointer can be dereferenced when signatures are being verified on PKCS7 signed or signedAndEnveloped data. After that, you call res.getBody() again. If not, this might be a bug. @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. Why do academics stay as adjuncts for years rather than move around? Correct; a null pointer is not a valid pointer for the C library functions. When you have a variable of non-primitive type, it is a reference to an object. that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. Using Kolmogorov complexity to measure difficulty of problems? This sounds indeed like a bug in the flow when an exception is raised. Making statements based on opinion; back them up with references or personal experience. (C11, S7.24.2.1). 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]. Is there a single-word adjective for "having exceptionally strong moral principles"? 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. We really appreciate your help. You can use Optional instead. I think that checking for user_data being NULL would be an improvement to the CS so long as there is an explicit mention that user_data being NULL is invalid even if length == 0. Can I tell police to wait and call a lawyer when served with a search warrant? That's true. Recovering from a blunder I made while emailing a professor. Find null smart pointer dereferences with the Clang Static Analyzer 3.7. Callable statement giving Null Pointer Exception - Oracle Forums ssize_t (*aio_read)(struct kiocb *, char __user *, size_t . To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Thanks, David! Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. Sonar false-positive on rule: Null pointers should not be dereferenced Connect and share knowledge within a single location that is structured and easy to search. 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). This issues is displayed by SonarQube. So we have to check all the arguments before performing any actions. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Write a semantic patch to nd cases where the result of calling kmalloc is dereferenced with no previous NULL pointer test. To learn more, see our tips on writing great answers. I suppose there is a question of "Is a pointer that points to 0 bytes valid?" Is there a single-word adjective for "having exceptionally strong moral principles"? In some situations, however, dereferencing a null pointer can lead to the execution of arbitrary code [Jack 2007,van Sprundel 2006]. sonar_etReines-CSDN 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). sonar-java. But when length of A is 1, the control never reaches the else block. Could I capture, and I would be able to glean much security information from the dump? can have the value zero on a call to that function. Making statements based on opinion; back them up with references or personal experience. I'd guess WG14 has considered these questions, but I haven't until now :). Search for vulnerabilities resulting from the violation of this rule on the CERT website. Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. )}"); It also adds assertions to document that certain other pointers must not be null. Ah, gotcha. It is useful to have a function with portable interface but platform-dependent implementation: extern bool invalid(const void *); 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. context.RaiseException , (/) We can see that at obj.run(), obj can not be null, but is pointed out by Sonar. Thanks for contributing an answer to Stack Overflow! Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. Your code needs to do something about the possible NullPointerException when some exception is caught, because in this scenario the responseDto will be null. When and how should I use a ThreadLocal variable? Thank you for clarifying your assertion until I understood it properly. 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. Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. What is the point of Thrower's Bandolier? Now (sonarqube java analyzer version 4.3.0.7717) it's supported and works fine. These can be: Invoking a method from a null object. // <------- 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. How can we prove that the supernatural or paranormal doesn't exist? [squid:S2259] False positive - "Null pointers should not be dereferenced" Phew, we're agreed here. - the incident has nothing to do with me; can I use this this way? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. At best, such an exception will cause abrupt program termination. 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". By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. ncdu: What's going on with this second size column? You can compare a pointer with NULL to test for the special condition. vegan) just to try it, does this inconvenience the caterers and staff? sonarlint, sonarLint (3.2.) Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. 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.. Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. 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>. JCP version in use: 2.6. positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. What is a NullPointerException, and how do I fix it? . 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 am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). () The user_data pointer could be invalid in other ways, such as pointing to freed memory. raiseException() return, Sonar Pointers in C Explained - They're Not as Difficult - freeCodeCamp.org Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. Its purpose is to serve as a special value for a pointer that could indicate a special condition in your program. This will normally lead to an unhandled error, resulting in a segmentation fault. With their flexibility, void pointers also bring some constraints. http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. Pointer members in structs are not checked. Hi Andreas, Thanks for the feedback. To learn more, see our tips on writing great answers. Pointer is so confusing : Stack with singly linked list in C - Stack 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). How do I align things in the following tabular environment? 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 there a proper earth ground point in this switch box? You're in a company-managed project. 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. SonarQube null pointers should not be dereferenced on try/catch Status: Dormant. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. 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. 1. Introduction - Understanding and Using C Pointers [Book] 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. At this point we define size as strlen(input_str) + 1. "After the incident", I started to be more careful not to trip over things. 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. Recovering from a blunder I made while emailing a professor. , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow Which @NotNull Java annotation should I use? Null Pointer Reference vs dereference pointers in arguments C++/C

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