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Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. 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. We really appreciate your help. rev2023.3.3.43278. Just because something is a pointer does not mean you should call delete . 3.Null pointers should not be derefer enced/accessed. 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. Is there a single-word adjective for "having exceptionally strong moral principles"? SonarJava. When you have a variable of non-primitive type, it is a reference to an object. The result of calling such a helper function should be . (In contrast, the case of passing 0 bytes to malloc is addressed in C11.) }. This likely means that youre on an ancient version of the Java analyzer. Null pointers should not be dereferenced. Status: Dormant. 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]. Software Engineering Institute Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. When and how should I use a ThreadLocal variable? To create a custom null validation method declare an attribute with name ValidatedNotNullAttribute and mark the parameter that is 4500 Fifth Avenue I've changed it to say null pointer instead of invalid pointer. A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). CWE-476: NULL Pointer Dereference: A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. Finally my method is returning a response with value of restTemplate. java I reordered that code example to do all the checks before allocations. As for copy vs pointer/reference - it depends. A reference to null should never be dereferenced/accessed. For example the following program doesn't compile. I'd guess null pointers are not valid, even though they point to 0 bytes. The same problem we will have with "Add at least one assertion to this test case." Does Java have support for multiline strings? What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? @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. That's true. Interactions/interfaces with C can't use references. Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. See C17 7.1.4p1, which says, in part: Each of the following statements applies unless explicitly stated otherwise in the detailed descriptions that follow: 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 pointerto 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. And the compliant solution guarantees that the pointer will be valid if the code calls memcpy(). Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". null(java.lang.NullPointerException) . 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? Mutually exclusive execution using std::atomic? 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. In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. For the time being, I would unfortunately recommend to mark as False Positive the issue. Aaron:I suspect we are talking past each other. 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. To learn more, see our tips on writing great 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 value 0 for the number of bytes to copy is not what causes the UB, it's the null pointer value which triggers it. Which version of SonarJava plugin do you have? that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. Can I tell police to wait and call a lawyer when served with a search warrant? This will normally lead to an unhandled error, resulting in a segmentation fault. Not the answer you're looking for? 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. 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 . res.getBody() == null || res.getBody().getServiceResult() == null). When and how should I use a ThreadLocal variable? In multithreaded programs, null pointer dereferences can violate cache coherency policies and can cause resource leaks. That interpretation of the standard is not supported universally. Dereferencing a null pointer is undefined behavior. - the incident has nothing to do with me; can I use this this way? Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, S2259: Null pointers should not be dereferenced, find the list of whitelisted methods here, Rule java:S2259: False-positive NullPointerException bug logged when variable is null-checked by an imported method, What is the issue you are observing, in details, What version of SonarSource products you are using, as well as the version of SonarJava. I believe in this case, either expression would work. 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. Is it possible to rotate a window 90 degrees if it has the same length and width? 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. There is a missing check for the return value from . An awesome tip to avoid NPE is to return empty strings or empty collections rather than 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" Making statements based on opinion; back them up with references or personal experience. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Find centralized, trusted content and collaborate around the technologies you use most. The 2nd NCCE/CS pair seems redundant with the first NCCE/CS pair. Why does the second compliant example permit using possibly-null pointers? This code also violates ERR33-C. Detect and handle standard library errors. Cause we need throw our own Runtime Exception, well-known methods wont help. 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. In C# and Java, all reference types can point to null. We can see that at obj.run(), obj can not be null, but is pointed out by Sonar. NullPointerException is a RuntimeException. 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. 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. Minimising the environmental effects of my dyson brain. 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. Connect and share knowledge within a single location that is structured and easy to search. 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. Trying to understand how to get this basic Fourier Series. Why is there a voltage on my HDMI and coaxial cables? 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. 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. You're in a company-managed project. LANG.MEM.NPDLANG.STRUCT.NTADLANG.STRUCT.UPD, Null pointer dereferenceNull test after dereferenceUnchecked parameter dereference, Can detect violations of this rule. There are many ways to resolve this. Using Kolmogorov complexity to measure difficulty of problems? Unlike reference types, pointer types are not tracked by the default garbage . I added a comment to explain that SIZE_MAX is the limit of size_t. Doing so will cause a NullPointerException to be thrown. name result . Finally, there is the matter of the compliant solution. Issues Components. Dereferencing a null pointer is undefined behavior, typically abnormal program termination. What sort of strategies would a medieval military use against a fantasy giant? Recovering from a blunder I made while emailing a professor. If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? In layman's terms, a null pointer is a pointer to an address in the memory space that does not have a meaningful value and cannot be referenced by the calling program, for whatever reason. We. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. specifies the length of the array for a function. Is there a solution to add special characters from software and how to do it, Acidity of alcohols and basicity of amines. We resolved it by adding our tools path in the white list, and repackaging it. rev2023.3.3.43278. Powered by Discourse, best viewed with JavaScript enabled. This topic was automatically closed 7 days after the last reply. Unfortunately, its actual state also has some limitations, like the one you are hitting here. When length is zero, it is probably unusable condition for this function. What are the effects of exceptions on performance in Java? 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. It is still a pointer though, to use it you just have to cast it to another kind of pointer first. Styling contours by colour and by line thickness in QGIS. Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. 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 also adds assertions to document that certain other pointers must not be null. Optimizers are optimizing based on this latitude and have been for years. IDE extension that lets you fix coding issues before they exist! Additionally, if input_str is a null pointer, the call to strlen() dereferences a null pointer, also resulting in undefined behavior. How to tell which packages are held back due to phased updates. That is only true if possibleNumbers contains no element.. BTW: none of these warnings are shown by . 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Believing that dereferencing NULL shouldn't crash the system doesn't make it true. Pittsburgh, PA 15213-2612 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 )}"); () Could I capture, and I would be able to glean much security information from the dump? which would allow us to systematically observe what you are having. Things go fine now. Is a PhD visitor considered as a visiting scholar? 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). If you call connect() function, it better do the connection, but failing simply because some ptr is NULL is not good behaviour -- failures should . 4. Alternate Terms Relationships Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. (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). My below code where I'm calling a stored procedure is giving a null pointer exception. There are other problems with this code, as is noted in the rule. The method isNR(minRating) is a helper method that validate among other things, if the object minRating is null. The only potential null is the return value of list(). Isn't easier just to check valid range of length? the Java one). (/). This sounds indeed like a bug in the flow when an exception is raised. In C, dereferencing a null pointer is undefined behavior. But even with this, the concerned object it tagged as a possible NullPointerException problem. The user_data pointer could be invalid in other ways, such as pointing to freed memory. Trying to understand how to get this basic Fourier Series. It looks like a logic bug, which can cause a memory leaking. How can we prove that the supernatural or paranormal doesn't exist? rev2023.3.3.43278. Does a summoned creature play immediately after being summoned by a ready action? How can I check before my flight that the cloud separation requirements in VFR flight rules are met? However there is no portable way to verify that the pointer is valid, other than checking for null. "After the incident", I started to be more careful not to trip over things. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? How to deal with "java.lang.OutOfMemoryError: Java heap space" error? 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. In some situations, however, dereferencing a null pointer can lead to the execution of arbitrary code [Jack 2007,van Sprundel 2006]. , . Key here (explains table format and definitions), EXP34-C = Union( CWE-690, list) where list =. Dereferencing > this null pointer may cause the kernel go wrong. 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. EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. sonarqube 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. . in above code, What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? 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. positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Is there a single-word adjective for "having exceptionally strong moral principles"? You can compare a pointer with NULL to test for the special condition. To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. sonarlint complains that Just a few words about the rule now. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. The null concept refers to the idea that a pointer can hold a special value that is not equal to another pointer. What is generic pointer? Does it just mean failing to correctly check if a value is null? The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. Then the reading of the buffer via bstr_printf() will then look at the pointer to process the final output. 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. There are many ways to resolve this. 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. But no where in that particular idiom would a NULL pointer necessarily be deferenced. That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. In my experience, there are reasons to check for a NULL pointer other than dereferencing it. Appropriate typecasting is necessary. Such long getter chains can also be replaced with Optional + map + ifPresent lambda style. Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. NULL vs Void Pointer - Null pointer is a value, while void pointer is a type. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. IDE extension that lets you fix coding issues before they exist! 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. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . If malloc() fails, it returns a null pointer that is assigned to c_str. I feel my situation is not as complicated. Basically, yes. The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. By explicitly teaching the C++ standard class behaviors we can make the Analyzer to find more bugs related to modern C++ code. Does Counterspell prevent from any further spells being cast on a given turn? A bug can cause them never to be reassigned. Pointer members in structs are not checked. Can I tell police to wait and call a lawyer when served with a search warrant? Why do academics stay as adjuncts for years rather than move around? 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. 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. Extended Description NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions. How can this new ban on drag possibly be considered constitutional? How do you ensure that a red herring doesn't violate Chekhov's gun? 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'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. SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. Trying to understand how to get this basic Fourier Series. 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. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? 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 */ But when length of A is 1, the control never reaches the else block. This code also violates ERR33-C. Detect and handle standard library errors. If you try to access any member variables or methods with that variable, you are trying to dereference it. How to use Slater Type Orbitals as a basis functions in matrix method correctly? 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. Goal What does "Could not find or load main class" mean? JCP version in use: 2.6. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. 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. SonarJava Version 5.9.2 (build 16552). 1 Answer Sorted by: 1 Your code is ok. Calls to extension methods are not reported because they can still operate on null values. 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. So the SIZE_MAX check was unnecessary. 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. Doing so will at best cause abrupt program termination, without the Passing ownership of something also requires pointers. return p == NULL || (char *)p < &_etext; Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. Please direct comments on this JSR to the Spec Lead (s) Team. Connect and share knowledge within a single location that is structured and easy to search. Hi @Michael! Here is our source code: Sign in to download full-size image Much like dereferencing a dangling (or wild) pointer leads to undefined behavior, dereferencing a null pointer also leads to undefined behavior. Now (sonarqube java analyzer version 4.3.0.7717) it's supported and works fine. 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. positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". A NULL pointer can be dereferenced when signatures are being verified on PKCS7 signed or signedAndEnveloped data. Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. isEmpty(Collection collection) void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. New replies are no longer allowed. Please explain: Without this, we wont be able to help you. 0 is certainly within the 'domain of the function' (a phrase defined by mathematics but not by C11), as copying 0 bytes is well-understood (although silly). This is a matter of style, and also following code walkthrough. 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?) Made code more compliant with other rules. 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. extern char _etext; Its purpose is to serve as a special value for a pointer that could indicate a special condition in your program. Likewise, pointers to freed memory are not valid. 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. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Now, you can find the list of whitelisted methods here. I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. If you preorder a special airline meal (e.g. Some Interesting Facts: 1) void pointers cannot be dereferenced. Find centralized, trusted content and collaborate around the technologies you use most. Should trycatch go inside or outside a loop? You're in a company-managed project. I would also guess that pointers that point to the one-past-the-end of an array are also invalid. Batch split images vertically in half, sequentially numbering the output files, Recovering from a blunder I made while emailing a professor. 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]. It's still illegal. (C11, S7.24.2.1). Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. Connect and share knowledge within a single location that is structured and easy to search. . By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Reports. io.NotSerializableException : java. Hello. Accessing or modifying a null object's field. Not the answer you're looking for? 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. I think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. Find centralized, trusted content and collaborate around the technologies you use most. 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. 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().