You're in a company-managed project. NULL vs Void Pointer - Null pointer is a value, while void pointer is a type. A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). Small typo nit: "such as if i t pointed to freed memory" meant to say "if it" instead (removing whitespace). In my experience, there are reasons to check for a NULL pointer other than dereferencing it. Not the answer you're looking for? "After the incident", I started to be more careful not to trip over things. Passing ownership of something also requires pointers. Are there tables of wastage rates for different fruit and veg? In order to fix this, just do the following: BodyType body=res.getBody (); if (body == null || body.getServiceResult () == null) { return; } You can then even reuse body after that. )}"); Accessing or modifying a null object's field. Void pointers cannot be dereferenced as any other pointer. In C# and Java, all reference types can point to null. 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. Software Engineering Institute As for copy vs pointer/reference - it depends. 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 To subscribe to this RSS feed, copy and paste this URL into your RSS reader. SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. But when length of A is 1, the control never reaches the else block. Null pointer should not be dereferenced . The return value from strchr() is often NULL, but the dev might know that a specific strchr() function call will not return NULL. 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". The idea is not to guarantee validity, but to catch a substantial number of problems that could occur. Is there a proper earth ground point in this switch box? 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. Much like dereferencing a dangling (or wild) pointer leads to undefined behavior, dereferencing a null pointer also leads to undefined behavior. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. It also uses the unsigned type size_t to pass the length parameter, ensuring that negative values are not passed to func(). In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. However, memory allocation > functions such as kstrdup() may fail and returns NULL. (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). Find centralized, trusted content and collaborate around the technologies you use most. Find centralized, trusted content and collaborate around the technologies you use most. At best, such an exception will cause abrupt program termination. Unfortunately, its actual state also has some limitations, like the one you are hitting here. Status: Dormant. 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. After that, you call res.getBody() again. Agreed. 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. 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. Best to cite C11 s7.24.2.1 here: The memcpy function copies n characters from the object pointed to by s2 into the object pointed to by s1. Currently I'm working with SonarQube solving issues but I'm facing a trouble to how handle null pointers that shouldn't be dereferenced. That is, sets equivalent to a proper subset via an all-structure-preserving bijection. 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. return p == NULL || (char *)p < &_etext; The issue arises when dereferenced pointers are used. If you try to access any member variables or methods with that variable, you are trying to dereference it. > Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to > the caller site. 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. rev2023.3.3.43278. I added a comment to explain that SIZE_MAX is the limit of size_t. Doing so will cause a NullReferenceException to be thrown. 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. Just a few words about the rule now. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . sonarLint (3.2.) Im having trouble understanding your problem. In the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. Many platforms can support testing for those also. SonarLint IntelliJ 4.0.0.2916 Java Rule 'Null pointers should not be dereferenced' I'm getting this fault in the next code when obj can't be null in any scenario. Goal Is there a single-word adjective for "having exceptionally strong moral principles"? To learn more, see our tips on writing great answers. sometimes FP occurs. I suggest that this topic needs to include calloc() and realloc() Refer to Linux man pages online for more enlightenment about malloc(), and friends. Also, the term 'pointer' is bad (but maybe it comes from the FindBugs tool): Java doesn't have pointers, it has references. Null pointer should not be dereferenced , Software project. ), 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. Thanks for contributing an answer to Stack Overflow! 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?) Passing a null pointer tomemcpy() would produce undefined behavior, even if the number of bytes to copy were 0. When and how should I use a ThreadLocal variable? Java Specification Participation Agreement version in use: 2.0. With their flexibility, void pointers also bring some constraints. Is it possible to rotate a window 90 degrees if it has the same length and width? Reports. Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". sonarqube By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java. That makes sense. 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?) Seems the analizer don't recognice the logic with the funcional object Optional. (/). A pointer is simply a variable that contains a memory address. Isn't easier just to check valid range of length? Put a new ResponseEntity is wrong because I won't know what will be the answer for the status of http. One could argue that all code examples would be redundant with the first pair. How do you ensure that a red herring doesn't violate Chekhov's gun? very old code or C code being worked into c++ may have functions that expect the user to delete the data. 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 . void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. Making statements based on opinion; back them up with references or personal experience. 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. A NULL pointer can be dereferenced when signatures are being verified on PKCS7 signed or signedAndEnveloped data. All rights are expressly reserved. Then we hit memcpy with length 0. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to bypass security measures. 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. I've changed it to say null pointer instead of invalid pointer. Software project. To learn more, see our tips on writing great answers. 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). Which version of SonarJava plugin do you have? io.NotSerializableException : java. "After the incident", I started to be more careful not to trip over things. Recovering from a blunder I made while emailing a professor. Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. In particular, ROSE ensures that any pointer returned by malloc(), calloc(), or realloc() is first checked for NULL before being used (otherwise, it is free()-ed). Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, It is a false positive, but it might be a good idea not to do the, Sonar false-positive on rule: Null pointers should not be dereferenced, How Intuit democratizes AI development across teams through reusability. The method isNR(minRating) is a helper method that validate among other things, if the object minRating is null. How do I align things in the following tabular environment? Dereferencing a null pointer results in undefined behavior. Finally, there is the matter of the compliant solution. For the time being, I would unfortunately recommend to mark as False Positive the issue. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. It also adds assertions to document that certain other pointers must not be null. 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 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(). sonarlint, sonarLint (3.2.) 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. In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. rev2023.3.3.43278. 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. specifies the length of the array for a function. NullPointerException is thrown when program attempts to use an object reference that has the null value. The final NCCE is actually more insidious than it seems at first. For example the following program doesn't compile. Making statements based on opinion; back them up with references or personal experience. Connect and share knowledge within a single location that is structured and easy to search. Now (sonarqube java analyzer version 4.3.0.7717) it's supported and works fine. HTTP request redirections should not be open to forging attacks Deserialization should not be vulnerable to injection attacks Endpoints should not be vulnerable to reflected cross-site scripting (XSS) attacks "CoSetProxyBlanket" and "CoInitializeSecurity" should not be used Database queries should not be vulnerable to injection attacks To subscribe to this RSS feed, copy and paste this URL into your RSS reader. PS: I also tried the code in android studio which uses Lint and got no warnings. I believe in this case, either expression would work. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. Depending on whether the pointer is valid (i.e. 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. 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. Asking for help, clarification, or responding to other answers. 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. It's still illegal. 3.Null pointers should not be derefer enced/accessed. Your code needs to do something about the possible NullPointerException when some exception is caught, because in this scenario the responseDto will be null. ssize_t (*aio_read)(struct kiocb *, char __user *, size_t . ncdu: What's going on with this second size column? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? PS: I also tried the code in android studio which uses Lint and got no warnings. EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. Trying to understand how to get this basic Fourier Series. Do "superinfinite" sets exist? But when length of A is 1, the control never reaches the else block. java Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. I'd guess null pointers are not valid, even though they point to 0 bytes. The user_data pointer could be invalid in other ways, such as pointing to freed memory. which would allow us to systematically observe what you are having. 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} Write a semantic patch to nd cases where the result of calling kmalloc is dereferenced with no previous NULL pointer test. Key here (explains table format and definitions), EXP34-C = Union( CWE-690, list) where list =. 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. }. A bug can cause them never to be reassigned. Trying to understand how to get this basic Fourier Series. It's a modular system with the . . This engine is validating execution paths and checking for non-null values or null-check along the way, exploring all the possibilities. Instead use String.valueOf (object). Does Counterspell prevent from any further spells being cast on a given turn? Please direct comments on this JSR to the Spec Lead (s) Team. 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. int changed to size_t and if size_t parameter's is zero, allocate one word. Since you cannot have a variable of type void, the pointer will not point to any data and therefore cannot be dereferenced. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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 sonar-java. 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. Is there a proper earth ground point in this switch box? minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). (from res.getBody().getServiceResult() ). There is no guarantee that subsequent invocations are returning the same value, thats why issue is raised. This will normally lead to an unhandled error, resulting in a segmentation fault. The method isNR (minRating) is a helper method that validate among other things, if the object minRating is null public boolean isNR (AgencyRating rating) { return rating == null || isNR (rating.getRatgCaam ()); } When I added the not null validation as sonar suggest. What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. Doing so will at best cause abrupt program termination, without the ii. // <------- 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. Pointer members in structs are not checked. Asking for help, clarification, or responding to other answers. 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. 2008-2023 SonarSource S.A., Switzerland. Extended Description NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions. The standard will simply copy 0 byteswhich is essentially a no-op. https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx We. Correct; a null pointer is not a valid pointer for the C library functions. 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 (?,?,?,?,?,?,?,? These can be: Invoking a method from a null object. When and how should I use a ThreadLocal variable? A reference to Nothing should never be dereferenced/accessed. In C/C++ speak, 'dereferencing' simply means getting the object that a pointer . isEmpty(Map map) But even with this, the concerned object it tagged as a possible NullPointerException problem. Mutually exclusive execution using std::atomic? When B is null, The control reaches inside the main if block only when length of A is 1. null(java.lang.NullPointerException) . My question is; is my solution incorrect? Is there a single-word adjective for "having exceptionally strong moral principles"? Alternate Terms Relationships At worst, it could expose debugging information that would be useful to an attacker or it could allow an Dereferencing > this null pointer may cause the kernel go wrong. 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. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? . Is the God of a monotheism necessarily omnipotent? SonarQube Version 6.7.2 (build 37468) SonarJava. in above code, This code also violates ERR33-C. Detect and handle standard library errors. Hi @Michael! How can we prove that the supernatural or paranormal doesn't exist? The solution that I recommend is not work with null returns or variables on Java, try to avoid it. In the meantime, Im locking this thread. 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. 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. The same problem we will have with "Add at least one assertion to this test case." Not the answer you're looking for? If you write [ref], then a null pointer is not allowed, but if you write [unique], then a null pointer is permitted. 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 does it mean that a reference must refer to an object, not a dereferenced null pointer? This solution also ensures that theuser_data pointer is not null. I suppose there is a question of "Is a pointer that points to 0 bytes valid?" Should trycatch go inside or outside a loop? res.getBody() == null || res.getBody().getServiceResult() == null). When B is null, The control reaches inside the main if block only when length of A is 1. Not the answer you're looking for? NULL vs Uninitialized pointer - An uninitialized pointer stores an undefined value. I have checked on multiple . 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). Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, SonarQube - Null Pointer Dereference Issue. IMHO, the rule title should be changed to something less general. 4500 Fifth Avenue Because a null pointer does not point to a meaningful object, an attempt to dereference(i.e., access the data stored at that memory location) a null pointer usually (but not always) causes a run-time error or immediate program crash. Null pointers should not be dereferenced. 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.. That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. Provide a self-contained reproducer (zipped project?) Search for vulnerabilities resulting from the violation of this rule on the CERT website. Sonar is ok. Sonar can't determine that the helper method did the null validation. If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? Trying to understand how to get this basic Fourier Series. If not, this might be a bug. (In contrast, the case of passing 0 bytes to malloc is addressed in C11.) 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. 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. The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). How can we let this pass? To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. All content is copyright protected. When you have a variable of non-primitive type, it is a reference to an object.
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