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 assert(!invalid(p)); // or whatever, bool invalid(const void *p) { In C# and Java, all reference types can point to null. Is the God of a monotheism necessarily omnipotent? 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(). You're in a company-managed project. Is a PhD visitor considered as a visiting scholar? raiseException() return, Sonar 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. It could be non-null the first time but not the second time, sonar does not know this. Interactions/interfaces with C can't use references. How can we prove that the supernatural or paranormal doesn't exist? 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. Is there a solution to add special characters from software and how to do it, Acidity of alcohols and basicity of amines. Can you please start a new thread and be more explicit about the issue you are observing. 1 Answer Sorted by: 1 Your code is ok. very old code or C code being worked into c++ may have functions that expect the user to delete the data. Sonar violation: Null pointers should not be dereferenced #7459 - GitHub 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. At worst, it could expose debugging information that would be useful to an attacker, or Key here (explains table format and definitions), EXP34-C = Union( CWE-690, list) where list =. assigning to dereferenced struct pointers To create a custom null validation method declare an attribute with name ValidatedNotNullAttribute and mark the parameter that is I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. When length is zero, it is probably unusable condition for this function. You can compare a pointer with NULL to test for the special condition. 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. please explain null pointer dereference [Solved] (Java in General forum int changed to size_t and if size_t parameter's is zero, allocate one word. How can we prove that the supernatural or paranormal doesn't exist? . Software project. FindBugs CORRECTNESS - 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. In the meantime, Im locking this thread. This solution also ensures that theuser_data pointer is not null. The libpng library implements its own wrapper to malloc() that returns a null pointer on error or on being passed a 0-byte-length argument. 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. 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. All content is copyright protected. Asking for help, clarification, or responding to other answers. Whats the grammar of "For those whose stories they are"? ncdu: What's going on with this second size column? The 2nd NCCE/CS pair seems redundant with the first NCCE/CS pair. Pointer members in structs are not checked. vegan) just to try it, does this inconvenience the caterers and staff? 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. PS: I also tried the code in android studio which uses Lint and got no warnings. But when length of A is 1, the control never reaches the else block. Software Engineering Institute rev2023.3.3.43278. The null concept refers to the idea that a pointer can hold a special value that is not equal to another pointer. Hi @Michael! (I think you cover that in a different rule.) If you preorder a special airline meal (e.g. There are other problems with this code, as is noted in the rule. This engine is validating execution paths and checking for non-null values or null-check along the way, exploring all the possibilities. In multithreaded programs, null pointer dereferences can violate cache coherency policies and can cause resource leaks. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. 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. [RSPEC-2259] - Jira I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. Thanks for the feedback. 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). I reordered that code example to do all the checks before allocations. 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 . Is it suspicious or odd to stand by the gate of a GA airport watching the planes? IDE extension that lets you fix coding issues before they exist! 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. All content is copyright protected. Not the answer you're looking for? Reports. 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. But what exactly does it mean to "dereference a null pointer"? It could be non-null the first time but not the second time, sonar does not know this. How can this new ban on drag possibly be considered constitutional? With their flexibility, void pointers also bring some constraints. It also adds assertions to document that certain other pointers must not be null. The user_data pointer could be invalid in other ways, such as pointing to freed memory. positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. Cause we need throw our own Runtime Exception, well-known methods wont help. 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. - the incident has nothing to do with me; can I use this this way? SonarQube - Null Pointer Dereference Issue - Sonar Community What is a NullPointerException, and how do I fix it? If copying takes place between objects that overlap, the behavior is undefined. This sounds indeed like a bug in the flow when an exception is raised. Handling Java NullPointerException and Best Practices - HowToDoInJava Thanks for contributing an answer to Stack Overflow! 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. sonarqube static-code-analysis Does a summoned creature play immediately after being summoned by a ready action? 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]. There is a missing check for the return value from . SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. And if there is no pointer_default declaration, then the default default is ref. Made code more compliant with other rules. If not, this might be a bug. That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. It looks like a logic bug, which can cause a memory leaking. Accessing or modifying a null object's field. Sonar false-positive on rule: Null pointers should not be dereferenced Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. [PATCH v2] vsprintf: Do not have bprintf dereference pointers After that, you call res.getBody() again. For example the following program doesn't compile. - the incident has nothing to do with me; can I use this this way? What is pointed to should only be deleted if it was created with new. Thanks for contributing an answer to Stack Overflow! minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). On many platforms, dereferencing a null pointer results in abnormal program termination, but this is not required by the standard. ssize_t (*aio_read)(struct kiocb *, char __user *, size_t . At best, such an exception will cause abrupt program termination. The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). , . In Java, a special null value can be assigned to an object reference. Currently I'm working with SonarQube solving issues but I'm facing a trouble to how handle null pointers that shouldn't be dereferenced. 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. On many platforms, dereferencing a null pointer results inabnormal program termination, but this is not required by the standard. Powered by Discourse, best viewed with JavaScript enabled. Dereferencing a null pointer is undefined behavior, typically abnormal program termination. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . [JAVA] 3.9 - FP for S2259 Null pointers should not be dereferenced If malloc() fails, it returns a null pointer that is assigned to c_str. Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). One could argue that all code examples would be redundant with the first pair. . LANG.MEM.NPDLANG.STRUCT.NTADLANG.STRUCT.UPD, Null pointer dereferenceNull test after dereferenceUnchecked parameter dereference, Can detect violations of this rule. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. squid:S2259 : A "NullPointerException" could be thrown; "dc" is Doing so will cause a NullReferenceException to be thrown. The method isNR (minRating) is a helper method that validate among other things, if the object minRating is null public boolean isNR (AgencyRating rating) { return rating == null || isNR (rating.getRatgCaam ()); } When I added the not null validation as sonar suggest. Reports. Answered: difference between a void pointer and a | bartleby The idea is not to guarantee validity, but to catch a substantial number of problems that could occur. sonar-java. Dereferencing > this null pointer may cause the kernel go wrong. Your assertion is not backed by the wording in the standard, nor by common implementer understanding. How to get rid of NullPointerException - freeCodeCamp.org We can not disable any rule, sonar do validation in "Sonar way" (actual name of profile :) ), so we will need to mark them "Wont fix" each time it appear again in new code. rev2023.3.3.43278. 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. Null - When a variable is declared as being a pointer to type void, it is known as a generic pointer. What is generic pointer? This compliant solution ensures that the pointer returned by png_malloc() is not null. Review and Fix Illegally Dereferenced Pointer Checks . ncdu: What's going on with this second size column? To learn more, see our tips on writing great answers. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to bypass security measures. Finally, there is the matter of the compliant solution. In the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. Since you cannot have a variable of type void, the pointer will not point to any data and therefore cannot be dereferenced. Here is our source code: Sign in to download full-size image Which @NotNull Java annotation should I use? 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. 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. SonarQube - Null Pointer Dereference Issue java simonsirak (Simon Sirak) June 14, 2018, 1:18pm 1 Hi! Find centralized, trusted content and collaborate around the technologies you use most. Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. (from res.getBody().getServiceResult() ). 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. I suggest that this topic needs to include calloc() and realloc() Refer to Linux man pages online for more enlightenment about malloc(), and friends. My below code where I'm calling a stored procedure is giving a null pointer exception. [PATCH 1/3] usb: ucsi: Fix NULL pointer deref in ucsi_connector_change() Hi Andreas, Thanks for the feedback. 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.) This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. Then the reading of the buffer via bstr_printf() will then look at the pointer to process the final output. Why pointers are not used in python? Explained by Sharing Culture Connect and share knowledge within a single location that is structured and easy to search. What are the effects of exceptions on performance in Java? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. [SONARJAVA-2808] - Jira - SonarSource 4500 Fifth Avenue That is why I explicitly check for this in my attempted solution. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. It also uses the unsigned type size_t to pass the length parameter, ensuring that negative values are not passed to func(). When and how should I use a ThreadLocal variable? OpenSSL Releases Security Update - NHS Digital Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. Sonar: Null pointers should not be dereferenced - Stack Overflow But no where in that particular idiom would a NULL pointer necessarily be deferenced. 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. Null Pointer Exception In Java - GeeksforGeeks - A computer science 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?) null(java.lang.NullPointerException) . 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} So Bar might not be initialized but then the last line of your example should not be evaluated in this case.