Java Specification Participation Agreement version in use: 2.0. Is there a single-word adjective for "having exceptionally strong moral principles"? How to deal with "java.lang.OutOfMemoryError: Java heap space" error? A reference to null should never be dereferenced/accessed. When length is zero, it is probably unusable condition for this function. That is, sets equivalent to a proper subset via an all-structure-preserving bijection. This code also violates ERR33-C. Detect and handle standard library errors. 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. The only potential null is the return value of list(). Two null pointers will always be equal to each other. Identify where the allocation occurs. The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. assert(!invalid(p)); // or whatever, bool invalid(const void *p) { The user_data pointer could be invalid in other ways, such as pointing to freed memory. 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 (?,?,?,?,?,?,?,? I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. Which ensures that the chunkdata pointer is valid, but makes no such check to the user_data pointer. What does "Could not find or load main class" mean? 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 positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. However there is no portable way to verify that the pointer is valid, other than checking for null. 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! Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. Thanks, David! Also, the term 'pointer' is bad (but maybe it comes from the FindBugs tool): Java doesn't have pointers, it has references. A pointer to null (the 0 memory address) should never be dereferenced/accessed. 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. Passing a null pointer tomemcpy() would produce undefined behavior, even if the number of bytes to copy were 0. 4. Recovering from a blunder I made while emailing a professor. Sonar is ok. Sonar can't determine that the helper method did the null validation. If malloc() fails, it returns a null pointer that is assigned to c_str. When a variable is declared as being a pointer to type void, it is known as a generic pointer. Is the God of a monotheism necessarily omnipotent? You can use Optional instead. can have the value zero on a call to that function. int changed to size_t and if size_t parameter's is zero, allocate one word. Im having trouble understanding your problem. 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. What are the effects of exceptions on performance in Java? By explicitly teaching the C++ standard class behaviors we can make the Analyzer to find more bugs related to modern C++ code. 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" How can we prove that the supernatural or paranormal doesn't exist? Search for vulnerabilities resulting from the violation of this rule on the CERT website. 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. Dereferencing a null pointer can lead to a denial of service. This latter use of pointers is a combined boolean/satellite: the pointer being non-null indicates "I have this sister object", and it provides that object. It also adds assertions to document that certain other pointers must not be null. EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. This will normally lead to an unhandled error, resulting in a segmentation fault. In Java, a special null value can be assigned to an object reference. Rule squid:S2259 is based on a Symbolic Execution (SE) engine. // <------- 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. rev2023.3.3.43278. points to memory allocated to the process) and what exactly was allocated there after the public key was freed, this may cause a segmentation fault or even execute code, which could again cause a segmentation fault, but might potentially be under the attacker's control. Cause we need throw our own Runtime Exception, well-known methods wont help. Write a semantic patch to nd cases where the result of calling kmalloc is dereferenced with no previous NULL pointer test. An awesome tip to avoid NPE is to return empty strings or empty collections rather than null. When and how should I use a ThreadLocal variable? Why does the second compliant example permit using possibly-null pointers? SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. Find centralized, trusted content and collaborate around the technologies you use most. NullPointerException is a RuntimeException. ssize_t (*aio_read)(struct kiocb *, char __user *, size_t . 1 Answer Sorted by: 1 Your code is ok. In the simplest case, this function just returns the result of calling kmalloc. And the compliant solution guarantees that the pointer will be valid if the code calls memcpy(). Good question! Making statements based on opinion; back them up with references or personal experience. (/). It could be non-null the first time but not the second time, sonar does not know this. Is null check needed before calling instanceof? On many platforms, dereferencing a null pointer results inabnormal program termination, but this is not required by the standard. 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. "After the incident", I started to be more careful not to trip over things. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? Its purpose is to serve as a special value for a pointer that could indicate a special condition in your program. To learn more, see our tips on writing great answers. Can I tell police to wait and call a lawyer when served with a search warrant? versions used (SonarQube, Scanner, language analyzer) 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. 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. However, memory allocation > functions such as kstrdup() may fail and returns NULL. 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. 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. 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. 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. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. LANG.MEM.NPDLANG.STRUCT.NTADLANG.STRUCT.UPD, Null pointer dereferenceNull test after dereferenceUnchecked parameter dereference, Can detect violations of this rule. So the SIZE_MAX check was unnecessary. Does Counterspell prevent from any further spells being cast on a given turn? Finally my method is returning a response with value of restTemplate. When you have a variable of non-primitive type, it is a reference to an object. As a result, this noncompliant code example is vulnerable to a null pointer dereference exploit, because null pointer dereferencing can be permitted on several platforms, for example, by using mmap(2) with the MAP_FIXED flag on Linux and Mac OS X, or by using the shmat() POSIX function with the SHM_RND flag [Liu 2009]. Basically, yes. We cannot understand how there could be a null pointer exception at the reported line. If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. You're in a company-managed project. This issues is displayed by SonarQube. All rights are expressly reserved. http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. I say "theoretical" because I have not successfully produced strings of this length in testing. 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. A pointer is simply a variable that contains a memory address. I suppose we can check that that is not null, but we cannot check that it is valid (in any portable way). null(java.lang.NullPointerException) . Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Dereferencing a null pointer results in undefined behavior. Made code more compliant with other rules. raiseException() return, Sonar 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. Appropriate typecasting is necessary. If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. 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 */ You need to benchmark. Do not use a null in a case where an object is required, https://gcc.gnu.org/gcc-4.9/porting_to.html, Prior to 2018-01-12: CERT: Unspecified Relationship, Pointer Casting and Pointer Type Changes [HFC], Dereferencing an out-of-domain pointer [nullref], Section 5.2.18, "Null-Pointer Dereference", Dereferencing null pointers that were not returned by a function. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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?) 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>. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . In C, dereferencing a null pointer is undefined behavior. Im currently using SonarQube version 5.6.6. better way to handle this is to store the result of method invocation in a variable. (from res.getBody().getServiceResult() ). The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. It looks like a logic bug, which can cause a memory leaking. 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. 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. Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. Thank you for clarifying your assertion until I understood it properly. What is generic pointer? A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). But when length of A is 1, the control never reaches the else block. Alternate Terms Relationships This sounds indeed like a bug in the flow when an exception is raised. Is a PhD visitor considered as a visiting scholar? All content is copyright protected. Explain about call by reference with an . Is it possible to rotate a window 90 degrees if it has the same length and width? Connect and share knowledge within a single location that is structured and easy to search. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. Whats the grammar of "For those whose stories they are"? This compliant solution ensures that the pointer returned by png_malloc() is not null. C# static code analysis: Null pointers should not be dereferenced Products In-IDE IDE extension that lets you fix coding issues before they exist! Powered by Discourse, best viewed with JavaScript enabled. 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 . How to use Slater Type Orbitals as a basis functions in matrix method correctly? SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. And if there is no pointer_default declaration, then the default default is ref. 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. This rule applies to all null pointers, regardless of which function returned them. . Avoid Returning null from Methods. On many platforms, dereferencing a null pointer results in abnormal program termination, but this is not required by the standard. Automated Detection Null pointer dereferences can happen in path-dependent ways. 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 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. Software project. What does it mean that a reference must refer to an object, not a dereferenced null pointer? 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 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. Not the answer you're looking for? Correct; a null pointer is not a valid pointer for the C library functions. At this point we define size as strlen(input_str) + 1. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? 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. isEmpty(Collection collection) This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. What is the point of Thrower's Bandolier? Which version of SonarJava plugin do you have? , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow How do you ensure that a red herring doesn't violate Chekhov's gun? 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. ncdu: What's going on with this second size column? I reordered that code example to do all the checks before allocations. But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. 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. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? Ticket opened : Thanks a lot for the minimalized reproducer ! Thanks for your relpy. 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. @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. The alert is related to the sonar rule : Null pointers should not be dereferenced. 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. To learn more, see our tips on writing great answers. I added a comment to explain that SIZE_MAX is the limit of size_t. I have checked on multiple . How do you ensure that a red herring doesn't violate Chekhov's gun? Trying to understand how to get this basic Fourier Series. 3.Null pointers should not be derefer enced/accessed. To create a custom null validation method declare an attribute with name ValidatedNotNullAttribute and mark the parameter that is 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.. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. The problem is that something like %*pbl which reads a bitmask, will save the pointer to the bitmask in the buffer. 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. Check whether a String is not Null and not Empty. This solution also ensures that theuser_data pointer is not null. Thanks for contributing an answer to Stack Overflow! When B is null, The control reaches inside the main if block only when length of A is 1. Instead use String.valueOf (object). Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. Hello. If not, this might be a bug. Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. These can be: Invoking a method from a null object. https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java. This is indeed an obvious False Positive from the rule. Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. It is still a pointer though, to use it you just have to cast it to another kind of pointer first. isEmpty(Map map) Trying to understand how to get this basic Fourier Series. If copying takes place between objects that overlap, the behavior is undefined. Your assertion is not backed by the wording in the standard, nor by common implementer understanding. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? rev2023.3.3.43278. I don't need to do this validation again. Whoops, you're right. The final NCCE is actually more insidious than it seems at first. minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). 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. Thanks for contributing an answer to Stack Overflow! That makes sense. 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. This sounds indeed like a bug in the flow when an exception is raised. context.RaiseException , (/) Please explain: Without this, we wont be able to help you. We really appreciate your help. 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. 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. Thanks for the feedback. The test was added to catch the possibly theoretical situation where the length of input_str was somehow the maximum size for size_t, and adding one to this size in the malloc expression (to allocated space for the trailing null byte) results in an integer overflow. Why does Mister Mxyzptlk need to have a weakness in the comics? ), 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). ), 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. 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. Reports. Some Interesting Facts: 1) void pointers cannot be dereferenced. 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. The method isNR(minRating) is a helper method that validate among other things, if the object minRating is null. Why are physically impossible and logically impossible concepts considered separate in terms of probability? Im very new to sonar, is there a way to add methods to the whitelist? Is there a single-word adjective for "having exceptionally strong moral principles"? So we have to check all the arguments before performing any actions. Void pointers cannot be dereferenced as any other pointer. So no checking of the length is necessary (besides preventing integer overflow, which the compliant solution does). 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. 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. Styling contours by colour and by line thickness in QGIS. 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. Which @NotNull Java annotation should I use? The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. We can see that at obj.run(), obj can not be null, but is pointed out by Sonar. Not the answer you're looking for? I would also guess that pointers that point to the one-past-the-end of an array are also invalid. In case the hash algorithm used for the signature is known to the OpenSSL library but the implementation of the hash algorithm is not available the digest initialization will fail. When exploring such methods, the engine then deduces behaviors regarding null-checking (among other things). Using platform-specific means (e.g. Is it possible to create a concave light? 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(). 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 This likely means that youre on an ancient version of the Java analyzer. public boolean isNameEmpty() { return getName().length() == 0; // Noncompliant; the result of getName() could be null, but isn't null-checked } . Solution 1, it looks like, today's solution tomorrow's problem. 2008-2023 SonarSource S.A., Switzerland. But passing 0 to memcpy() is not one of them. Accessing or modifying a null object's field. Is there a proper earth ground point in this switch box? Making statements based on opinion; back them up with references or personal experience.