What does "Could not find or load main class" mean? C# static code analysis: Null pointers should not be dereferenced Products In-IDE IDE extension that lets you fix coding issues before they exist! Explain about call by reference with an . However, memory allocation > functions such as kstrdup() may fail and returns NULL. ssize_t (*aio_read)(struct kiocb *, char __user *, size_t . We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Hello. 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). @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. 1 Answer Sorted by: 1 Your code is ok. What sort of strategies would a medieval military use against a fantasy giant? 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. Connect and share knowledge within a single location that is structured and easy to search. Styling contours by colour and by line thickness in QGIS. Aaron:I suspect we are talking past each other. You can compare a pointer with NULL to test for the special condition. I suppose we can check that that is not null, but we cannot check that it is valid (in any portable way). Dereferencing a null pointer results in undefined behavior. You're in a company-managed project. . 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. Are there tables of wastage rates for different fruit and veg? That is why I explicitly check for this in my attempted solution. After that, you call res.getBody() again. When you have a variable of non-primitive type, it is a reference to an object. 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. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Sonar false-positive on rule: Null pointers should not be dereferenced, Null Pointer Dereference issue not detected when the pointer is returned by another function. There are many ways to resolve this. Sonar is ok. NullPointerException is thrown when program attempts to use an object reference that has the null value. Ticket opened : Thanks a lot for the minimalized reproducer ! Passing ownership of something also requires pointers. . 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. Share Improve this answer Follow answered Oct 5, 2017 at 16:27 Basically, yes. In my experience, there are reasons to check for a NULL pointer other than dereferencing it. NULL vs Uninitialized pointer - An uninitialized pointer stores an undefined value. (In contrast, the case of passing 0 bytes to malloc is addressed in C11.) Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. context.RaiseException , (/) ii. It also uses the unsigned type size_t to pass the length parameter, ensuring that negative values are not passed to func(). Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Shouldn't the function check all pointers before dereferencing them or passing them to another function? Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. rev2023.3.3.43278. To create a custom null validation method declare an attribute with name ValidatedNotNullAttribute and mark the parameter that is Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. 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. http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. which would allow us to systematically observe what you are having. Which ensures that the chunkdata pointer is valid, but makes no such check to the user_data pointer. Does it just mean failing to correctly check if a value is null? SonarJava. In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. uninitialized reference-type class members. minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). assert(!invalid(p)); // or whatever, bool invalid(const void *p) { What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. All rights are expressly reserved. 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. 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. Carnegie Mellon University If copying takes place between objects that overlap, the behavior is undefined. (C11, S7.24.2.1). Which version of SonarJava plugin do you have? Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? It could be non-null the first time but not the second time, sonar does not know this. If not, this might be a bug. Obviously the value of that pointer could have changed since the . The final NCCE is actually more insidious than it seems at first. When and how should I use a ThreadLocal variable? Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. best, such an exception will cause abrupt program termination. This noncompliant code example is derived from a real-world example taken from a vulnerable version of the libpng library as deployed on a popular ARM-based cell phone [Jack 2007]. New replies are no longer allowed. 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 We really appreciate your help. If you try to access any member variables or methods with that variable, you are trying to dereference it. IDE extension that lets you fix coding issues before they exist! Is there a proper earth ground point in this switch box? )}"); SonarQube - Null Pointer Dereference Issue java simonsirak (Simon Sirak) June 14, 2018, 1:18pm 1 Hi! 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). res.getBody() == null || res.getBody().getServiceResult() == null). 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" Agreed. How to deal with "java.lang.OutOfMemoryError: Java heap space" error? sonarqube isEmpty(Collection collection) I believe in this case, either expression would work. This solution also ensures that theuser_data pointer is not null. 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. Cause we need throw our own Runtime Exception, well-known methods wont help. 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(). Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? There are other problems with this code, as is noted in the rule. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? very old code or C code being worked into c++ may have functions that expect the user to delete the data. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? Why are physically impossible and logically impossible concepts considered separate in terms of probability? return p == NULL || (char *)p < &_etext; 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. Alternate Terms Relationships Unfortunately, its actual state also has some limitations, like the one you are hitting here. 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 . }. LANG.MEM.NPDLANG.STRUCT.NTADLANG.STRUCT.UPD, Null pointer dereferenceNull test after dereferenceUnchecked parameter dereference, Can detect violations of this rule. Find centralized, trusted content and collaborate around the technologies you use most. 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 Thanks for contributing an answer to Stack Overflow! 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. Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. ), NPD.CHECK.CALL.MIGHTNPD.CHECK.CALL.MUSTNPD.CHECK.MIGHTNPD.CHECK.MUSTNPD.CONST.CALLNPD.CONST.DEREFNPD.FUNC.CALL.MIGHTNPD.FUNC.CALL.MUSTNPD.FUNC.MIGHTNPD.FUNC.MUSTNPD.GEN.CALL.MIGHTNPD.GEN.CALL.MUSTNPD.GEN.MIGHTNPD.GEN.MUSTRNPD.CALLRNPD.DEREF, 45 D, 123 D, 128 D, 129 D, 130 D, 131 D, 652 S, Checks for use of null pointers (rule partially covered). Is the God of a monotheism necessarily omnipotent? Trying to understand how to get this basic Fourier Series. https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. Please explain: Without this, we wont be able to help you. If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? Doing so will cause a NullReferenceException to be thrown. Dereferencing a null pointer is undefined behavior, typically abnormal program termination. Interactions/interfaces with C can't use references. // <------- 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. Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. Put a new ResponseEntity is wrong because I won't know what will be the answer for the status of http. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. In some situations, however, dereferencing a null pointer can lead to the execution of arbitrary code [Jack 2007,van Sprundel 2006]. If you preorder a special airline meal (e.g. As for today, the SE engine is able to explore non-overridable methods (static, for instance), when declared in the same file being analyzed. Write a semantic patch to nd cases where the result of calling kmalloc is dereferenced with no previous NULL pointer test. Software Engineering Institute However there is no portable way to verify that the pointer is valid, other than checking for null. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. 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. Batch split images vertically in half, sequentially numbering the output files, Recovering from a blunder I made while emailing a professor. All content is copyright protected. Is it possible to create a concave light? context.RaiseException . I added a comment to explain that SIZE_MAX is the limit of size_t. rev2023.3.3.43278. 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). (from res.getBody().getServiceResult() ). Isn't easier just to check valid range of length? 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). At 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. And the compliant solution guarantees that the pointer will be valid if the code calls memcpy(). Asking for help, clarification, or responding to other answers. Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). [4] Good question! What is generic pointer? 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. - the incident has nothing to do with me; can I use this this way? When B is null, The control reaches inside the main if block only when length of A is 1. This sounds indeed like a bug in the flow when an exception is raised. Ah, gotcha. Its purpose is to serve as a special value for a pointer that could indicate a special condition in your program. Thank you for clarifying your assertion until I understood it properly. 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.. Avoid Returning null from Methods. 4500 Fifth Avenue Just a few words about the rule now. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. 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. This engine is validating execution paths and checking for non-null values or null-check along the way, exploring all the possibilities. 1 Answer Sorted by: 2 Your code needs to do something about the possible NullPointerException when some exception is caught, because in this scenario the responseDto will be null. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? Void pointers cannot be dereferenced as any other pointer. I'd guess null pointers are not valid, even though they point to 0 bytes. Dereferencing a null pointer is undefined behavior. 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. io.NotSerializableException : java. PS: I also tried the code in android studio which uses Lint and got no warnings. The same problem we will have with "Add at least one assertion to this test case." Many platforms can support testing for those also. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Whats the grammar of "For those whose stories they are"? . Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. Issues Components. Check whether a String is not Null and not Empty. Correct; a null pointer is not a valid pointer for the C library functions. The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. This rule applies to all null pointers, regardless of which function returned them. 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. You can use Optional instead. When exploring such methods, the engine then deduces behaviors regarding null-checking (among other things). PS: I also tried the code in android studio which uses Lint and got no warnings. The alert is related to the sonar rule : Null pointers should not be dereferenced. If you call connect() function, it better do the connection, but failing simply because some ptr is NULL is not good behaviour -- failures should . The null concept refers to the idea that a pointer can hold a special value that is not equal to another pointer. 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. Reports. Provide a self-contained reproducer (zipped project?) Mutually exclusive execution using std::atomic? 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. To learn more, see our tips on writing great answers. False-positives are pointed out in other SO posts (1 & 2), where nulls are involved across functions and procedures. To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. 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. 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". How do I align things in the following tabular environment? Dereferencing a null pointer can lead to a denial of service. 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. Making statements based on opinion; back them up with references or personal experience. What is null pointer exception in android. This likely means that youre on an ancient version of the Java analyzer. {"serverDuration": 214, "requestCorrelationId": "084acdc104f21c51"}, EXP34-C. Do not dereference null pointers, Clever Attack Exploits Fully-Patched Linux Kernel, ERR33-C. Detect and handle standard library errors, one compliant and one non-compliant example, CERT Oracle Secure Coding Standard for Java, EXP01-J. Null pointer should not be dereferenced . 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. 2008-2023 SonarSource S.A., Switzerland. 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. , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow To subscribe to this RSS feed, copy and paste this URL into your RSS reader. java Using Kolmogorov complexity to measure difficulty of problems? How can we prove that the supernatural or paranormal doesn't exist? Made code more compliant with other rules. 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. The return value from strchr() is often NULL, but the dev might know that a specific strchr() function call will not return NULL. I added an assertion to that compliant code example. In multithreaded programs, null pointer dereferences can violate cache coherency policies and can cause resource leaks. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. 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. Additionally, if input_str is a null pointer, the call to strlen() dereferences a null pointer, also resulting in undefined behavior. 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! Null pointer should not be dereferenced , The standard will simply copy 0 byteswhich is essentially a no-op. Using Kolmogorov complexity to measure difficulty of problems? When and how should I use a ThreadLocal variable? I think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. That's true. 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. By explicitly teaching the C++ standard class behaviors we can make the Analyzer to find more bugs related to modern C++ code. This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. I suppose there is a question of "Is a pointer that points to 0 bytes valid?" Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. It does not point to any area of memory. . It's a modular system with the . 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. 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. attacker to bypass security measures. positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". Trying to understand how to get this basic Fourier Series. A reference to null should never be dereferenced/accessed. Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. 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. Is there a single-word adjective for "having exceptionally strong moral principles"? My main problem is because I'm doing a restTemplate.exchange with try-catch and declaring a variable with null value before the clause try and then using it inside the try. That interpretation of the standard is not supported universally. 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.) IMHO, the rule title should be changed to something less general. What are the effects of exceptions on performance in Java? Making statements based on opinion; back them up with references or personal experience. How do you ensure that a red herring doesn't violate Chekhov's gun? Asking for help, clarification, or responding to other answers. 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. The expected result here is solve the issue with sonarqube. When I added the not null validation as sonar suggest. Then the reading of the buffer via bstr_printf() will then look at the pointer to process the final output. static-code-analysis I reordered that code example to do all the checks before allocations. sonarlint, sonarLint (3.2.) I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. Reports. A reference to null should never be dereferenced/accessed. 11 Sep, 2006. In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. Can I tell police to wait and call a lawyer when served with a search warrant? Finally my method is returning a response with value of restTemplate. With their flexibility, void pointers also bring some constraints. The issue arises when dereferenced pointers are used. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. Identify where the allocation occurs. SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. 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. void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. 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.
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