null pointers should not be dereferenced

When and how should I use a ThreadLocal variable? Search for vulnerabilities resulting from the violation of this rule on the CERT website. Pointer Arithmetic in c - Unit - 4 1. Define pointer. Explain about the I suggest that this topic needs to include calloc() and realloc() Refer to Linux man pages online for more enlightenment about malloc(), and friends. 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. This engine is validating execution paths and checking for non-null values or null-check along the way, exploring all the possibilities. When c_str is dereferenced in memcpy(), the program exhibits undefined behavior. 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. Provide a self-contained reproducer (zipped project?) Replacing broken pins/legs on a DIP IC package, Bulk update symbol size units from mm to map units in rule-based symbology, How do you get out of a corner when plotting yourself into a corner. It is useful to have a function with portable interface but platform-dependent implementation: extern bool invalid(const void *); Issues Components. Why is there a voltage on my HDMI and coaxial cables? I suppose we can check that that is not null, but we cannot check that it is valid (in any portable way). In Java, a special null value can be assigned to an object reference. return p == NULL || (char *)p < &_etext; Doing so will cause a NullReferenceException to be thrown. What is a NullPointerException, and how do I fix it?,What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them? - the incident has nothing to do with me; can I use this this way? 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. 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. I reordered that code example to do all the checks before allocations. SonarQube null pointers should not be dereferenced on try/catch This rule applies to all null pointers, regardless of which function returned them. Unlike reference types, pointer types are not tracked by the default garbage . 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. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to bypass security measures. The issue arises when dereferenced pointers are used. 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. Hi Andreas, Thanks for the feedback. If not, this might be a bug. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Dereferencing a null pointer is undefined behavior, typically abnormal program termination. Null - OpenSSL Releases Security Update - NHS Digital @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. squid:S2259 : A "NullPointerException" could be thrown; "dc" is There are other problems with this code, as is noted in the rule. Goal 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. To learn more, see our tips on writing great answers. Extended Description NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions. The idea is not to guarantee validity, but to catch a substantial number of problems that could occur. Analysis of Haiku Operating System (BeOS Family) by PVS-Studio. Part 1 My question is; is my solution incorrect? Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. Making statements based on opinion; back them up with references or personal experience. Because null pointer dereferencing is undefined behavior, the compiler (GCC in this case) can optimize away the if (!tun) check because it is performed after tun->sk is accessed, implying that tun is non-null. 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. (C11, S7.24.2.1). (/). 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. Whats the grammar of "For those whose stories they are"? Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". 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. A null pointer stores a defined value, but one that is defined by the environment to not be a valid address for any member or object. Why void pointer cannot be dereferenced? Explained by Sharing Culture 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. - the incident has nothing to do with me; can I use this this way? To learn more, see our tips on writing great answers. Pointer is so confusing : Stack with singly linked list in C - Stack S2259: Null pointers should not be dereferenced - Sonar Community 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). What sort of strategies would a medieval military use against a fantasy giant? 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. Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. 3.7. Hello. http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. At this point we define size as strlen(input_str) + 1. 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. The null concept refers to the idea that a pointer can hold a special value that is not equal to another pointer. Why does the second compliant example permit using possibly-null pointers? False-positives are pointed out in other SO posts (1 & 2), where nulls are involved across functions and procedures. 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). Is there a single-word adjective for "having exceptionally strong moral principles"? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. It could be non-null the first time but not the second time, sonar does not know this. 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. In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. rev2023.3.3.43278. how to handle Sonarlint java:S2259 (Null pointers should not be An awesome tip to avoid NPE is to return empty strings or empty collections rather than null. How handle the initialization of "responseDto" without "null" because is throwing the issue on sonar. rev2023.3.3.43278. context.RaiseException . That is, sets equivalent to a proper subset via an all-structure-preserving bijection. To create a custom null validation method declare an attribute with name ValidatedNotNullAttribute and mark the parameter that is That makes sense. SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. the Java one). Dereferencing a null pointer results in undefined behavior. rev2023.3.3.43278. Things go fine now. Why are physically impossible and logically impossible concepts considered separate in terms of probability? Phew, we're agreed here. In C# and Java, all reference types can point to null. The user_data pointer could be invalid in other ways, such as pointing to freed memory. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. As for copy vs pointer/reference - it depends. This is indeed an obvious False Positive from the rule. If malloc() fails, it returns a null pointer that is assigned to c_str. 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?) Coverity Prevent cannot discover all violations of this rule, so further verification is necessary, Detects when NULL is dereferenced (Array of pointers is not checked. When exploring such methods, the engine then deduces behaviors regarding null-checking (among other things). Void pointers cannot be dereferenced as any other pointer. It does not point to any area of memory. COMP-PROG-MODULE-5-6-REVIEWER.pdf - Pointers to string But even with this, the concerned object it tagged as a possible NullPointerException problem. Sonar violation: Null pointers should not be dereferenced #7459 - GitHub Sonar false-positive on rule: Null pointers should not be dereferenced Is it suspicious or odd to stand by the gate of a GA airport watching the planes? Please explain: Without this, we wont be able to help you. This compliant solution ensures that the pointer returned by png_malloc() is not null. That is only true if possibleNumbers contains no element.. BTW: none of these warnings are shown by . If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? 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. This sounds indeed like a bug in the flow when an exception is raised. ", 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". In my experience, there are reasons to check for a NULL pointer other than dereferencing it. You need to benchmark. Shouldn't the function check all pointers before dereferencing them or passing them to another function? IDE extension that lets you fix coding issues before they exist! Reference vs dereference pointers in arguments C++/C But no where in that particular idiom would a NULL pointer necessarily be deferenced. Ticket opened : Thanks a lot for the minimalized reproducer ! Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. Minimising the environmental effects of my dyson brain. minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). A NULL pointer can be dereferenced when signatures are being verified on PKCS7 signed or signedAndEnveloped data. How do you ensure that a red herring doesn't violate Chekhov's gun? Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. The null pointer check for writing or dereferencing should be a compiler flag or library setting. SonarQube Version 6.7.2 (build 37468) The purpose of a NULL pointer is not to cause a processor exception when it is dereferenced (although that is nice to have for debugging.) We really appreciate your help. How can we prove that the supernatural or paranormal doesn't exist? Essentially, this code and the previous dereference disagree as to whether this value is allowed to be null. A reference to null should never be dereferenced/accessed. 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 . The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). Find centralized, trusted content and collaborate around the technologies you use most. How to tell which packages are held back due to phased updates. How can we prove that the supernatural or paranormal doesn't exist? Obviously the value of that pointer could have changed since the . (I think you cover that in a different rule.) That interpretation of the standard is not supported universally. 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 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. In the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. It's still illegal. Pointers in C Explained - They're Not as Difficult - freeCodeCamp.org 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. Doing so will cause a NullPointerException to be thrown. But what exactly does it mean to "dereference a null pointer"? Java Specification Participation Agreement version in use: 2.0. Im having trouble understanding your problem. Calls to extension methods are not reported because they can still operate on null values. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. (In contrast, the case of passing 0 bytes to malloc is addressed in C11.) sonarlint complains that And if there is no pointer_default declaration, then the default default is ref. Is it possible to create a concave light? I feel my situation is not as complicated. very old code or C code being worked into c++ may have functions that expect the user to delete the data. 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. 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). See "Clever Attack Exploits Fully-Patched Linux Kernel" [Goodin 2009] for an example of a code execution exploit that resulted from a null pointer dereference. Possible fix: Assign a valid address to the pointer in all branches of the conditional statement.. Pointer can point to dynamically allocated memory. Currently I'm working with SonarQube solving issues but I'm facing a trouble to how handle null pointers that shouldn't be dereferenced. 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. raiseException() return, Sonar Rule squid:S2259 is based on a Symbolic Execution (SE) engine. Connect and share knowledge within a single location that is structured and easy to search. 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. There are many ways to resolve this. I have a sonar alert on this call minRating.getRatgCaam(). Your assertion is not backed by the wording in the standard, nor by common implementer understanding. If that variable hasn't had a reference assigned, it's a null reference, which (for internal/historical reasons) is referred to as a null pointer. Does Counterspell prevent from any further spells being cast on a given turn? strongSwan - strongSwan Vulnerability (CVE-2023-26463) 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 is a feature that we are currently heavily working on to be able to switch off such kind of false positives. The correct idiom is to only allocate storage if the pointer is currently NULL. Null pointer should not be dereferenced , I believe in this case, either expression would work. The fact that you can't pass a null (no object) with a reference parameter can be a reason to use a pointer instead. Making statements based on opinion; back them up with references or personal experience. When B is null, The control reaches inside the main if block only when length of A is 1. The expected result here is solve the issue with sonarqube. 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. Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. 4. We resolved it by adding our tools path in the white list, and repackaging it. Discover SonarLint SaaS Setup is effortless and analysis is automatic for most languages Discover SonarCloud Self-Hosted Fast, accurate analysis; enterprise scalability Discover SonarQube Secrets ABAP Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. The 2nd NCCE/CS pair seems redundant with the first NCCE/CS pair. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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 say "theoretical" because I have not successfully produced strings of this length in testing. 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Asking for help, clarification, or responding to other answers. You can compare a pointer with NULL to test for the special condition. Automated Detection Null pointer dereferences can happen in path-dependent ways. This sounds indeed like a bug in the flow when an exception is raised.

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