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. context.RaiseException . ucsi->connector gets dereferenced by both ucsi_connector_change() and ucsi_resume(), both check for ucsi->connector being NULL in case ucsi_init() has not finished yet; or in case ucsi_init() has failed. We really appreciate your 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" sonarlint, sonarLint (3.2.) Automated Detection Null pointer dereferences can happen in path-dependent ways. 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. best, such an exception will cause abrupt program termination. 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. ncdu: What's going on with this second size column? 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. Is there a proper earth ground point in this switch box? If not, this might be a bug. How can we prove that the supernatural or paranormal doesn't exist? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. Search for vulnerabilities resulting from the violation of this rule on the CERT website. Two null pointers will always be equal to each other. Since you cannot have a variable of type void, the pointer will not point to any data and therefore cannot be dereferenced. Asking for help, clarification, or responding to other answers. rev2023.3.3.43278. 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. Its purpose is to serve as a special value for a pointer that could indicate a special condition in your program. For example the following program doesn't compile. 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). Find centralized, trusted content and collaborate around the technologies you use most. SonarQube Version 6.7.2 (build 37468) If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? The null concept refers to the idea that a pointer can hold a special value that is not equal to another pointer. Find centralized, trusted content and collaborate around the technologies you use most. I'd guess null pointers are not valid, even though they point to 0 bytes. 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. What does "Could not find or load main class" mean? (In contrast, the case of passing 0 bytes to malloc is addressed in C11.) When I scan with sonar-lint in idea, it seams white list is useful, but when use sonar-scanner, always FP, org.springframework.util.CollectionUtils#isEmpty What is a NullPointerException, and how do I fix it?,What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them? Is there a proper earth ground point in this switch box? When B is null, The control reaches inside the main if block only when length of A is 1. (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). Dereferencing a null pointer can lead to a denial of service. Recovering from a blunder I made while emailing a professor. When you have a variable of non-primitive type, it is a reference to an object. 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. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to bypass security measures. And if there is no pointer_default declaration, then the default default is ref. validated for null in your method declaration with it: 2008-2023 SonarSource S.A., Switzerland. Just because something is a pointer does not mean you should call delete . , . What does it mean that a reference must refer to an object, not a dereferenced null pointer? public boolean isNameEmpty() { return getName().length() == 0; // Noncompliant; the result of getName() could be null, but isn't null-checked } . 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. 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. Does it just mean failing to correctly check if a value is null? Connect and share knowledge within a single location that is structured and easy to search. Such long getter chains can also be replaced with Optional + map + ifPresent lambda style. There are many ways to resolve this. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . The problem is that something like %*pbl which reads a bitmask, will save the pointer to the bitmask in the buffer. So the SIZE_MAX check was unnecessary. Java Specification Participation Agreement version in use: 2.0. If you try to access any member variables or methods with that variable, you are trying to dereference it. 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. Is there a proper earth ground point in this switch box? You need to benchmark. Unlike reference types, pointer types are not tracked by the default garbage . ", Eclipse - Sonar S2629 possible false positive with new String, SonarQube null pointers should not be dereferenced on try/catch, getTextContent() through "Null pointers should not be dereferenced". In C, dereferencing a null pointer is undefined behavior. The fact that you can't pass a null (no object) with a reference parameter can be a reason to use a pointer instead. 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]. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. I think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. All content is copyright protected. return p == NULL || (char *)p < &_etext; 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. Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. I'd guess WG14 has considered these questions, but I haven't until now :). But when length of A is 1, the control never reaches the else block. 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. 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. It is useful to have a function with portable interface but platform-dependent implementation: extern bool invalid(const void *); Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. The final NCCE is actually more insidious than it seems at first. that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. Asking for help, clarification, or responding to other answers. 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. sonarLint (3.2.) Styling contours by colour and by line thickness in QGIS. which version of SonarQube are you using? The same problem we will have with "Add at least one assertion to this test case." Powered by Discourse, best viewed with JavaScript enabled. That is why I explicitly check for this in my attempted solution. To learn more, see our tips on writing great answers. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. Shouldn't the function check all pointers before dereferencing them or passing them to another function? Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. uninitialized reference-type class members. I suppose there is a question of "Is a pointer that points to 0 bytes valid?" You can use Optional instead. PS: I also tried the code in android studio which uses Lint and got no warnings. 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?) 1 Answer Sorted by: 1 Your code is ok. @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. 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. 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. 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. However there is no portable way to verify that the pointer is valid, other than checking for null. 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. 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]. And fwstr > is dereferenced in the following codes. In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. Is there a single-word adjective for "having exceptionally strong moral principles"? For the time being, I would unfortunately recommend to mark as False Positive the issue. That is only true if possibleNumbers contains no element.. BTW: none of these warnings are shown by . I think that checking for user_data being NULL would be an improvement to the CS so long as there is an explicit mention that user_data being NULL is invalid even if length == 0. The expected result here is solve the issue with sonarqube. , NPE : null-, . In my experience, there are reasons to check for a NULL pointer other than dereferencing it. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Can you please start a new thread and be more explicit about the issue you are observing. When and how should I use a ThreadLocal variable? This is a matter of style, and also following code walkthrough. PS: I also tried the code in android studio which uses Lint and got no warnings. In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, SonarQube - Null Pointer Dereference Issue. in above code, 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. Reports. SonarJava Version 5.9.2 (build 16552). isEmpty(Map map) Why is there a voltage on my HDMI and coaxial cables? rev2023.3.3.43278. 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. Ah, gotcha. Small typo nit: "such as if i t pointed to freed memory" meant to say "if it" instead (removing whitespace). Basically, yes. Reports. Optimizers are optimizing based on this latitude and have been for years. Can I tell police to wait and call a lawyer when served with a search warrant? Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). Asking for help, clarification, or responding to other answers. LANG.MEM.NPDLANG.STRUCT.NTADLANG.STRUCT.UPD, Null pointer dereferenceNull test after dereferenceUnchecked parameter dereference, Can detect violations of this rule. How can this new ban on drag possibly be considered constitutional? 3.7. A reference to null should never be dereferenced/accessed. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. So no checking of the length is necessary (besides preventing integer overflow, which the compliant solution does). I suppose we can check that that is not null, but we cannot check that it is valid (in any portable way). Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. If you write [ref], then a null pointer is not allowed, but if you write [unique], then a null pointer is permitted. Then the reading of the buffer via bstr_printf() will then look at the pointer to process the final output. Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. static-code-analysis Thanks for contributing an answer to Stack Overflow! () SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. IDE extension that lets you fix coding issues before they exist! How do you ensure that a red herring doesn't violate Chekhov's gun? ii. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? The solution that I recommend is not work with null returns or variables on Java, try to avoid it. Additionally, if input_str is a null pointer, the call to strlen() dereferences a null pointer, also resulting in undefined behavior. New replies are no longer allowed. Can I tell police to wait and call a lawyer when served with a search warrant? java https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx [4] 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. Do "superinfinite" sets exist? A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. 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. Why does Mister Mxyzptlk need to have a weakness in the comics? So we have to check all the arguments before performing any actions. 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. To learn more, see our tips on writing great answers. Calls to extension methods are not reported because they can still operate on null values. Instead use String.valueOf (object). Depending on whether the pointer is valid (i.e. Likewise, pointers to freed memory are not valid. 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. I have checked on multiple . Goal But when length of A is 1, the control never reaches the else block. Connect and share knowledge within a single location that is structured and easy to search. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. What is pointed to should only be deleted if it was created with new. The user_data pointer could be invalid in other ways, such as pointing to freed memory. Because a null pointer does not point to a meaningful object, an attempt to dereference(i.e., access the data stored at that memory location) a null pointer usually (but not always) causes a run-time error or immediate program crash. Write a semantic patch to nd cases where the result of calling kmalloc is dereferenced with no previous NULL pointer test. This likely means that youre on an ancient version of the Java analyzer. If copying takes place between objects that overlap, the behavior is undefined. 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.. 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. Is it possible to create a concave light? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. Made code more compliant with other rules. In multithreaded programs, null pointer dereferences can violate cache coherency policies and can cause resource leaks. int changed to size_t and if size_t parameter's is zero, allocate one word. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. Thanks for your relpy. It does not point to any area of memory. positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. Finally my method is returning a response with value of restTemplate. Using Kolmogorov complexity to measure difficulty of problems? But what exactly does it mean to "dereference a null pointer"? This will normally lead to an unhandled error, resulting in a segmentation fault. In C/C++ speak, 'dereferencing' simply means getting the object that a pointer . How do I align things in the following tabular environment? How can we let this pass? ), 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. 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. What is null pointer exception in android. 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). It could be non-null the first time but not the second time, sonar does not know this. 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. The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). can have the value zero on a call to that function. Many platforms can support testing for those also. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? 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. - the incident has nothing to do with me; can I use this this way? Dereferencing > this null pointer may cause the kernel go wrong. Making statements based on opinion; back them up with references or personal experience. Connect and share knowledge within a single location that is structured and easy to search. . Is it possible to create a concave light? 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. Void pointers cannot be dereferenced as any other pointer. Pittsburgh, PA 15213-2612
Not the answer you're looking for? 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. attacker to bypass security measures. Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. C static code analysis: Null pointers should not be dereferenced C static code analysis Unique rules to find Bugs, Vulnerabilities, Security Hotspots, and Code Smells in your C code All rules 311 Vulnerability 13 Bug 74 Security Hotspot 18 Code Smell 206 Quick Fix 14 Tags "memset" should not be used to delete sensitive data Vulnerability it could allow an attacker to bypass security measures. Making statements based on opinion; back them up with references or personal experience. {"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. Put a new ResponseEntity is wrong because I won't know what will be the answer for the status of http. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? 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. res.getBody() == null || res.getBody().getServiceResult() == null). "After the incident", I started to be more careful not to trip over things. Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". This compliant solution eliminates the null pointer deference by initializing sk to tun->sk following the null pointer check. If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? How to tell which packages are held back due to phased updates. Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. 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. How to use Slater Type Orbitals as a basis functions in matrix method correctly? Batch split images vertically in half, sequentially numbering the output files, Recovering from a blunder I made while emailing a professor. name result . That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. 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. Explain about call by reference with an . To create a custom null validation method declare an attribute with name ValidatedNotNullAttribute and mark the parameter that is Hi Andreas, Thanks for the feedback. EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. I feel my situation is not as complicated. In the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. Not the answer you're looking for? In the code, we check the not nullity with java.util.Objects.nonNull(). Share Improve this answer Follow answered Oct 5, 2017 at 16:27 Unfortunately, its actual state also has some limitations, like the one you are hitting here. Using Kolmogorov complexity to measure difficulty of problems? When B is null, The control reaches inside the main if block only when length of A is 1. 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. Passing ownership of something also requires pointers. What sort of strategies would a medieval military use against a fantasy giant? I added an assertion to that compliant code example. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. Then we hit memcpy with length 0. 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. We cannot understand how there could be a null pointer exception at the reported line. Im currently using SonarQube version 5.6.6. better way to handle this is to store the result of method invocation in a variable. 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. What is the point of Thrower's Bandolier? 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>. raiseException() return, Sonar 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. When c_str is dereferenced in memcpy(), the program exhibits undefined behavior.