But even with this, the concerned object it tagged as a possible NullPointerException problem. that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. We resolved it by adding our tools path in the white list, and repackaging it. Just a few words about the rule now. For the time being, I would unfortunately recommend to mark as False Positive the issue. That makes sense. Java Specification Participation Agreement version in use: 2.0. 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. In the code, we check the not nullity with java.util.Objects.nonNull(). Making statements based on opinion; back them up with references or personal experience. 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. 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. Is null check needed before calling instanceof? Basically, yes. 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 Currently I'm working with SonarQube solving issues but I'm facing a trouble to how handle null pointers that shouldn't be dereferenced. 4. But when length of A is 1, the control never reaches the else block. Two null pointers will always be equal to each other. sonarLint (3.2.) http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. the Java one). io.NotSerializableException : java. At worst, it could expose debugging information that would be useful to an attacker or it could allow an Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. Why do academics stay as adjuncts for years rather than move around? Now, you can find the list of whitelisted methods here. What is null pointer exception in android. Instead use String.valueOf (object). 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" Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". public boolean isNameEmpty() { return getName().length() == 0; // Noncompliant; the result of getName() could be null, but isn't null-checked } . But passing 0 to memcpy() is not one of them. The final NCCE is actually more insidious than it seems at first. 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. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. To learn more, see our tips on writing great answers. 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. Optimizers are optimizing based on this latitude and have been for years. IMHO, the rule title should be changed to something less general. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). Just because something is a pointer does not mean you should call delete . best, such an exception will cause abrupt program termination. Find centralized, trusted content and collaborate around the technologies you use most. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. The null concept refers to the idea that a pointer can hold a special value that is not equal to another pointer. I suppose there is a question of "Is a pointer that points to 0 bytes valid?" This rule applies to all null pointers, regardless of which function returned them. At Coverity Prevent cannot discover all violations of this rule, so further verification is necessary, Detects when NULL is dereferenced (Array of pointers is not checked. This compliant solution ensures that the pointer returned by png_malloc() is not null. This compliant solution eliminates the null pointer deference by initializing sk to tun->sk following the null pointer check. How can this new ban on drag possibly be considered constitutional? This likely means that youre on an ancient version of the Java analyzer. 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. 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. Im having trouble understanding your problem. When a variable is declared as being a pointer to type void, it is known as a generic pointer. 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. 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. void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. 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. Ticket opened : Thanks a lot for the minimalized reproducer ! Which version of SonarJava plugin do you have? In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. If you call connect() function, it better do the connection, but failing simply because some ptr is NULL is not good behaviour -- failures should . Note that it doesn't know how to check for non-heap, non-stack. . Unfortunately, its actual state also has some limitations, like the one you are hitting here. How do you ensure that a red herring doesn't violate Chekhov's gun? Thanks for contributing an answer to Stack Overflow! Does Counterspell prevent from any further spells being cast on a given turn? Doing so will cause a NullReferenceException to be thrown. Passing ownership of something also requires pointers. Why does Mister Mxyzptlk need to have a weakness in the comics? Using platform-specific means (e.g. When I added the not null validation as sonar suggest. A reference to Nothing should never be dereferenced/accessed. 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 standard will simply copy 0 byteswhich is essentially a no-op. Are there tables of wastage rates for different fruit and veg? Should trycatch go inside or outside a loop? Is it possible to create a concave light? So no checking of the length is necessary (besides preventing integer overflow, which the compliant solution does). 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. 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. How to tell which packages are held back due to phased updates. It looks like a logic bug, which can cause a memory leaking. Software project. And if there is no pointer_default declaration, then the default default is ref. This code also violates ERR33-C. Detect and handle standard library errors. 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). 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. You're in a company-managed project. 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. In Java, a special null value can be assigned to an object reference. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, how to handle Sonarlint java:S2259 (Null pointers should not be dereferenced), How Intuit democratizes AI development across teams through reusability. See "Clever Attack Exploits Fully-Patched Linux Kernel" [Goodin 2009] for an example of a code execution exploit that resulted from a null pointer dereference. 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. Then the reading of the buffer via bstr_printf() will then look at the pointer to process the final output. 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. 1 Answer Sorted by: 1 Your code is ok. Styling contours by colour and by line thickness in QGIS. I've changed it to say null pointer instead of invalid pointer. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow Dereferencing a null pointer is undefined behavior, typically abnormal program termination. positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. When exploring such methods, the engine then deduces behaviors regarding null-checking (among other things). There are other problems with this code, as is noted in the rule. Key here (explains table format and definitions), EXP34-C = Union( CWE-690, list) where list =. positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Thank you for clarifying your assertion until I understood it properly. Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. It is useful to have a function with portable interface but platform-dependent implementation: extern bool invalid(const void *); PS: I also tried the code in android studio which uses Lint and got no warnings. At best, such an exception will cause abrupt program termination. Does it just mean failing to correctly check if a value is null? - the incident has nothing to do with me; can I use this this way? Doing so will at best cause abrupt program termination, without the 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). 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. https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java. "After the incident", I started to be more careful not to trip over things. Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). 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. In C# and Java, all reference types can point to null. What is a serialVersionUID and why should I use it? IDE extension that lets you fix coding issues before they exist! 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. . Whoops, you're right. The correct idiom is to only allocate storage if the pointer is currently NULL. By 'valid pointers' I mean that both src and dest pointers are not null and they both point to non-overlapping arrays containing at least n bytes each. Asking for help, clarification, or responding to other answers. On many platforms, dereferencing a null pointer results inabnormal program termination, but this is not required by the standard. It does not point to any area of memory. Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. It also uses the unsigned type size_t to pass the length parameter, ensuring that negative values are not passed to func(). 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. 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?) By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Recovering from a blunder I made while emailing a professor. That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. rev2023.3.3.43278. Why are physically impossible and logically impossible concepts considered separate in terms of probability? 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? 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.. ssize_t (*aio_read)(struct kiocb *, char __user *, size_t . At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . All rights are expressly reserved. can have the value zero on a call to that function. This engine is validating execution paths and checking for non-null values or null-check along the way, exploring all the possibilities. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Using Kolmogorov complexity to measure difficulty of problems? Whats the grammar of "For those whose stories they are"? Making statements based on opinion; back them up with references or personal experience. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? ncdu: What's going on with this second size column? You're in a company-managed project. Is a PhD visitor considered as a visiting scholar? Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. > Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to > the caller site. Carnegie Mellon University We can see that at obj.run(), obj can not be null, but is pointed out by Sonar. 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. 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. 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. it could allow an attacker to bypass security measures. Also, the term 'pointer' is bad (but maybe it comes from the FindBugs tool): Java doesn't have pointers, it has references. False-positives are pointed out in other SO posts (1 & 2), where nulls are involved across functions and procedures. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Small typo nit: "such as if i t pointed to freed memory" meant to say "if it" instead (removing whitespace). In the simplest case, this function just returns the result of calling kmalloc. versions used (SonarQube, Scanner, language analyzer) 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. isEmpty(Collection collection) New replies are no longer allowed. , . In the meantime, Im locking this thread. In C, dereferencing a null pointer is undefined behavior. How handle the initialization of "responseDto" without "null" because is throwing the issue on sonar. 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. 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. . Sonar is ok. 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. Making statements based on opinion; back them up with references or personal experience. Why is there a voltage on my HDMI and coaxial cables? In C/C++ speak, 'dereferencing' simply means getting the object that a pointer . Pittsburgh, PA 15213-2612 NULL vs Void Pointer - Null pointer is a value, while void pointer is a type. 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. When B is null, The control reaches inside the main if block only when length of A is 1. I reordered that code example to do all the checks before allocations. Hi Andreas, Thanks for the feedback. The null pointer check for writing or dereferencing should be a compiler flag or library setting. @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. You need to benchmark. Asking for help, clarification, or responding to other answers. 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. The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). Finally, there is the matter of the compliant solution. Could I capture, and I would be able to glean much security information from the dump? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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 . Batch split images vertically in half, sequentially numbering the output files, Recovering from a blunder I made while emailing a professor. I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. My below code where I'm calling a stored procedure is giving a null pointer exception. 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.