null pointers should not be dereferenced null pointers should not be dereferenced

"After the incident", I started to be more careful not to trip over things. Is there a single-word adjective for "having exceptionally strong moral principles"? Additionally, if input_str is a null pointer, the call to strlen() dereferences a null pointer, also resulting in undefined behavior. Thanks, David! 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). Asking for help, clarification, or responding to other answers. Do not dereference null pointers Created by Jeffrey Gennari, last modified by Jill Britton on Jan 18, 2023 Dereferencing a null pointer is undefined behavior. sonarLint (3.2.) (C11, S7.24.2.1). A pointer is simply a variable that contains a memory address. Shouldn't the function check all pointers before dereferencing them or passing them to another function? Issues Components. 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. IDE extension that lets you fix coding issues before they exist! A NULL pointer can be dereferenced when signatures are being verified on PKCS7 signed or signedAndEnveloped data. You're in a company-managed project. SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. 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. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. IDE extension that lets you fix coding issues before they exist! When B is null, The control reaches inside the main if block only when length of A is 1. Connect and share knowledge within a single location that is structured and easy to search. sonarqube Not the answer you're looking for? In my experience, there are reasons to check for a NULL pointer other than dereferencing it. This is a feature that we are currently heavily working on to be able to switch off such kind of false positives. 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. 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. static-code-analysis Note that it doesn't know how to check for non-heap, non-stack. - the incident has nothing to do with me; can I use this this way? 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. Unfortunately, its actual state also has some limitations, like the one you are hitting here. At this point we define size as strlen(input_str) + 1. Pointer members in structs are not checked. 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. Should trycatch go inside or outside a loop? How can I check before my flight that the cloud separation requirements in VFR flight rules are met? 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. Why does the second compliant example permit using possibly-null pointers? How can this new ban on drag possibly be considered constitutional? The result of calling such a helper function should be . What sort of strategies would a medieval military use against a fantasy giant? This code also violates ERR33-C. Detect and handle standard library errors. util.regex.Matcher, java - Swing .getParent() . 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. Null pointers should not be dereferenced. . Just because something is a pointer does not mean you should call delete . 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. Using Kolmogorov complexity to measure difficulty of problems? 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. Which @NotNull Java annotation should I use? Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. @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. However there is no portable way to verify that the pointer is valid, other than checking for null. What is null pointer exception in android. PS: I also tried the code in android studio which uses Lint and got no warnings. Hello. I've changed it to say null pointer instead of invalid pointer. Is it possible to create a concave light? 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. versions used (SonarQube, Scanner, language analyzer) Connect and share knowledge within a single location that is structured and easy to search. Now, you can find the list of whitelisted methods here. Is there a proper earth ground point in this switch box? 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 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). 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. I suppose there is a question of "Is a pointer that points to 0 bytes valid?" 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. Software Engineering Institute And fwstr > is dereferenced in the following codes. To learn more, see our tips on writing great answers. 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. (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). 4500 Fifth Avenue Currently I'm working with SonarQube solving issues but I'm facing a trouble to how handle null pointers that shouldn't be dereferenced. So no checking of the length is necessary (besides preventing integer overflow, which the compliant solution does). What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. Dereferencing a null pointer is undefined behavior. sometimes FP occurs. Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. We. Pittsburgh, PA 15213-2612 By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. I suppose we can check that that is not null, but we cannot check that it is valid (in any portable way). In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. Software project. Dereferencing > this null pointer may cause the kernel go wrong. I believe in this case, either expression would work. Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. A reference to Nothing should never be dereferenced/accessed. Ah, gotcha. So the SIZE_MAX check was unnecessary. 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. Minimising the environmental effects of my dyson brain. Description: This JSR will work to develop standard annotations (such as @NonNull) that can be applied to Java programs to assist tools that detect software defects. > Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to > the caller site. A reference to null should never be dereferenced/accessed. Such long getter chains can also be replaced with Optional + map + ifPresent lambda style. ), 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). isEmpty(Collection collection) In C/C++ speak, 'dereferencing' simply means getting the object that a pointer . Explain about call by reference with an . 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. I have checked on multiple . Status: Dormant. I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. 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 Put a new ResponseEntity is wrong because I won't know what will be the answer for the status of http. At best, such an exception will cause abrupt program termination. 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. 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 . Asking for help, clarification, or responding to other answers. One could argue that all code examples would be redundant with the first pair. 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. 2008-2023 SonarSource S.A., Switzerland. The idea is not to guarantee validity, but to catch a substantial number of problems that could occur. This issues is displayed by SonarQube. The problem is that something like %*pbl which reads a bitmask, will save the pointer to the bitmask in the buffer. The alert is related to the sonar rule : Null pointers should not be dereferenced. (I think you cover that in a different rule.) Identify where the allocation occurs. We really appreciate your help. Rule squid:S2259 is based on a Symbolic Execution (SE) engine. The null concept refers to the idea that a pointer can hold a special value that is not equal to another pointer. But what exactly does it mean to "dereference a null pointer"? 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. Do "superinfinite" sets exist? 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. . , NPE : null-, . How do you ensure that a red herring doesn't violate Chekhov's gun? best, such an exception will cause abrupt program termination. 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). It looks like a logic bug, which can cause a memory leaking. Im very new to sonar, is there a way to add methods to the whitelist? A bug can cause them never to be reassigned. Calls to extension methods are not reported because they can still operate on null values. 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. That is, sets equivalent to a proper subset via an all-structure-preserving bijection. Please explain: Without this, we wont be able to help you. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. 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. All content is copyright protected. To learn more, see our tips on writing great answers. Thus we should check > this kstrdup() operation. public boolean isNameEmpty() { return getName().length() == 0; // Noncompliant; the result of getName() could be null, but isn't null-checked } . positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. How to use Slater Type Orbitals as a basis functions in matrix method correctly? The null pointer check for writing or dereferencing should be a compiler flag or library setting. Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. it could allow an attacker to bypass security measures. These can be: Invoking a method from a null object. Thanks for your relpy. What is a serialVersionUID and why should I use it? With their flexibility, void pointers also bring some constraints. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Now (sonarqube java analyzer version 4.3.0.7717) it's supported and works fine. Isn't easier just to check valid range of length? 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} Are there tables of wastage rates for different fruit and veg? 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. java 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 (?,?,?,?,?,?,?,? NULL vs Uninitialized pointer - An uninitialized pointer stores an undefined value. When and how should I use a ThreadLocal variable? Aaron:I suspect we are talking past each other. C static code analysis: Null pointers should not be dereferenced C static code analysis Unique rules to find Bugs, Vulnerabilities, Security Hotspots, and Code Smells in your C code All rules 311 Vulnerability 13 Bug 74 Security Hotspot 18 Code Smell 206 Quick Fix 14 Tags "memset" should not be used to delete sensitive data Vulnerability The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. You need to benchmark. 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. () So Bar might not be initialized but then the last line of your example should not be evaluated in this case. Trying to understand how to get this basic Fourier Series. 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. The same problem we will have with "Add at least one assertion to this test case." Can you please start a new thread and be more explicit about the issue you are observing. A reference to null should never be dereferenced/accessed. 11 Sep, 2006. I feel my situation is not as complicated. This topic was automatically closed 7 days after the last reply. Please direct comments on this JSR to the Spec Lead (s) Team. 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. 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?) https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java. It's still illegal. I would also guess that pointers that point to the one-past-the-end of an array are also invalid. 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. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. 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. At best, such an exception will cause abrupt program termination. Small typo nit: "such as if i t pointed to freed memory" meant to say "if it" instead (removing whitespace). And the semantics, as I said, are different. Your code needs to do something about the possible NullPointerException when some exception is caught, because in this scenario the responseDto will be null. The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). In C, dereferencing a null pointer is undefined behavior. We cannot understand how there could be a null pointer exception at the reported line. sonarlint complains that Since you cannot have a variable of type void, the pointer will not point to any data and therefore cannot be dereferenced. How can we prove that the supernatural or paranormal doesn't exist? Check whether a String is not Null and not Empty. Carnegie Mellon University // <------- 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. very old code or C code being worked into c++ may have functions that expect the user to delete the data. Provide a self-contained reproducer (zipped project?) Search for vulnerabilities resulting from the violation of this rule on the CERT website. Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. Reports. , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow The solution that I recommend is not work with null returns or variables on Java, try to avoid it. Off by one error: It is the third example. ", 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". We resolved it by adding our tools path in the white list, and repackaging it. 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(). Just a few words about the rule now. Appropriate typecasting is necessary. 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. SonarQube - Null Pointer Dereference Issue java simonsirak (Simon Sirak) June 14, 2018, 1:18pm 1 Hi! As for copy vs pointer/reference - it depends. rev2023.3.3.43278. Here is our source code: Sign in to download full-size image Unlike reference types, pointer types are not tracked by the default garbage . What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? That's true. uninitialized reference-type class members. (from res.getBody().getServiceResult() ). After that, you call res.getBody() again. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). Share Improve this answer Follow answered Oct 5, 2017 at 16:27 I added an assertion to that compliant code example. 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. Batch split images vertically in half, sequentially numbering the output files, Recovering from a blunder I made while emailing a professor. To learn more, see our tips on writing great answers. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. And if there is no pointer_default declaration, then the default default is ref. Hi @Michael! Cause we need throw our own Runtime Exception, well-known methods wont help. Why do academics stay as adjuncts for years rather than move around? You can compare a pointer with NULL to test for the special condition. )}"); If malloc() fails, it returns a null pointer that is assigned to c_str. A pointer to null (the 0 memory address) should never be dereferenced/accessed. 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 . At worst, it could expose debugging information that would be useful to an attacker or it could allow an 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 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 sounds indeed like a bug in the flow when an exception is raised. Doing so will cause a NullReferenceException to be thrown. In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. 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 at best cause abrupt program termination, without the That makes sense. 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.