null pointers should not be dereferenced

Rule squid:S2259 is based on a Symbolic Execution (SE) engine. Do "superinfinite" sets exist? Unlike reference types, pointer types are not tracked by the default garbage . 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. Can you please start a new thread and be more explicit about the issue you are observing. 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). 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. ), NPD.CHECK.CALL.MIGHTNPD.CHECK.CALL.MUSTNPD.CHECK.MIGHTNPD.CHECK.MUSTNPD.CONST.CALLNPD.CONST.DEREFNPD.FUNC.CALL.MIGHTNPD.FUNC.CALL.MUSTNPD.FUNC.MIGHTNPD.FUNC.MUSTNPD.GEN.CALL.MIGHTNPD.GEN.CALL.MUSTNPD.GEN.MIGHTNPD.GEN.MUSTRNPD.CALLRNPD.DEREF, 45 D, 123 D, 128 D, 129 D, 130 D, 131 D, 652 S, Checks for use of null pointers (rule partially covered). Share Improve this answer Follow answered Oct 5, 2017 at 16:27 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. Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. The null pointer check for writing or dereferencing should be a compiler flag or library setting. 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). Is it possible to rotate a window 90 degrees if it has the same length and width? Hello. Obviously the value of that pointer could have changed since the . The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. NULL vs Void Pointer - Null pointer is a value, while void pointer is a type. Seems the analizer don't recognice the logic with the funcional object Optional. A NULL pointer can be dereferenced when signatures are being verified on PKCS7 signed or signedAndEnveloped data. But passing 0 to memcpy() is not one of them. On many platforms, dereferencing a null pointer results inabnormal program termination, but this is not required by the standard. I don't need to do this validation again. raiseException() return, Sonar In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. Sonar is ok. Sonar can't determine that the helper method did the null validation. NullPointerException is thrown when program attempts to use an object reference that has the null value. Instead use String.valueOf (object). You can use Optional instead. 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. 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 code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? It also adds assertions to document that certain other pointers must not be null. 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. A reference to null should never be dereferenced/accessed. So the SIZE_MAX check was unnecessary. What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. All content is copyright protected. I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). You need to benchmark. void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. 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. 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. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. 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. Powered by Discourse, best viewed with JavaScript enabled. There is a missing check for the return value from . 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. Thanks for contributing an answer to Stack Overflow! 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} How do I align things in the following tabular environment? It also reinforces the notion to the reader that any time you see arithmetic in an allocation expression, you need to think about corner-cases. PS: I also tried the code in android studio which uses Lint and got no warnings. We resolved it by adding our tools path in the white list, and repackaging it. Finally my method is returning a response with value of restTemplate. Also, the term 'pointer' is bad (but maybe it comes from the FindBugs tool): Java doesn't have pointers, it has references. Is null check needed before calling instanceof? These can be: Invoking a method from a null object. The problem is that something like %*pbl which reads a bitmask, will save the pointer to the bitmask in the buffer. It also uses the unsigned type size_t to pass the length parameter, ensuring that negative values are not passed to func(). Not the answer you're looking for? JCP version in use: 2.6. What does "Could not find or load main class" mean? Dereferencing a null pointer can lead to a denial of service. If you try to access any member variables or methods with that variable, you are trying to dereference it. Correct; a null pointer is not a valid pointer for the C library functions. Just a few words about the rule now. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? However there is no portable way to verify that the pointer is valid, other than checking for null. 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). SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. I added an assertion to that compliant code example. Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. I've changed it to say null pointer instead of invalid pointer. Does it just mean failing to correctly check if a value is null? Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". Aaron:I suspect we are talking past each other. very old code or C code being worked into c++ may have functions that expect the user to delete the data. A reference to null should never be dereferenced/accessed. A reference to Nothing should never be dereferenced/accessed. 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. LANG.MEM.NPDLANG.STRUCT.NTADLANG.STRUCT.UPD, Null pointer dereferenceNull test after dereferenceUnchecked parameter dereference, Can detect violations of this rule. Trying to understand how to get this basic Fourier Series. Connect and share knowledge within a single location that is structured and easy to search. The method isNR(minRating) is a helper method that validate among other things, if the object minRating is null. Why are physically impossible and logically impossible concepts considered separate in terms of probability? When B is null, The control reaches inside the main if block only when length of A is 1. sonarqube 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. We. Making statements based on opinion; back them up with references or personal experience. ROSE does not handle cases where an allocation is assigned to an lvalue that is not a variable (such as a struct member or C++ function call returning a reference), Finds instances where a pointer is checked against NULL and then later dereferenced, Identifies functions that can return a null pointer but are not checked, Identifies code that dereferences a pointer and then checks the pointer against NULL, Can find the instances where NULL is explicitly dereferenced or a pointer is checked againstNULL but then dereferenced anyway. . Is there a proper earth ground point in this switch box? . Automated Detection Null pointer dereferences can happen in path-dependent ways. SonarJava. https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java. This is indeed an obvious False Positive from the rule. IDE extension that lets you fix coding issues before they exist! Interactions/interfaces with C can't use references. Why does the second compliant example permit using possibly-null pointers? I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. There are other problems with this code, as is noted in the rule. Connect and share knowledge within a single location that is structured and easy to search. 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. What are the effects of exceptions on performance in Java? Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. 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 Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. Possible fix: Assign a valid address to the pointer in all branches of the conditional statement.. Pointer can point to dynamically allocated memory. The only potential null is the return value of list(). , NPE : null-, . Much like dereferencing a dangling (or wild) pointer leads to undefined behavior, dereferencing a null pointer also leads to undefined behavior. Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). Just because something is a pointer does not mean you should call delete . "After the incident", I started to be more careful not to trip over things. Does Java have support for multiline strings? 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 . Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, SonarQube - Null Pointer Dereference Issue. What does it mean that a reference must refer to an object, not a dereferenced null pointer? IDE extension that lets you fix coding issues before they exist! Shouldn't the function check all pointers before dereferencing them or passing them to another function? Things go fine now. versions used (SonarQube, Scanner, language analyzer) When length is zero, it is probably unusable condition for this function. Pointer members in structs are not checked. The same problem we will have with "Add at least one assertion to this test case." positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. 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. Issues Components. IMHO, the rule title should be changed to something less general. 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. Using Kolmogorov complexity to measure difficulty of problems? 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. When I added the not null validation as sonar suggest. EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. public boolean isNameEmpty() { return getName().length() == 0; // Noncompliant; the result of getName() could be null, but isn't null-checked } . 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. attacker to bypass security measures. Off by one error: It is the third example. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? I would also guess that pointers that point to the one-past-the-end of an array are also invalid. Thank you for clarifying your assertion until I understood it properly. Explain about call by reference with an . 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. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. 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. int changed to size_t and if size_t parameter's is zero, allocate one word. Which version of SonarJava plugin do you have? In C# and Java, all reference types can point to null. Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. To learn more, see our tips on writing great answers. 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. (from res.getBody().getServiceResult() ). Is a PhD visitor considered as a visiting scholar? To learn more, see our tips on writing great answers. Should trycatch go inside or outside a loop? 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>. Trying to understand how to get this basic Fourier Series. This will normally lead to an unhandled error, resulting in a segmentation fault. That is, sets equivalent to a proper subset via an all-structure-preserving bijection. Using Kolmogorov complexity to measure difficulty of problems? On many platforms, dereferencing a null pointer results in abnormal program termination, but this is not required by the standard. Thanks for the feedback. Software Engineering Institute 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. 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. http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. Such long getter chains can also be replaced with Optional + map + ifPresent lambda style. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Is there a single-word adjective for "having exceptionally strong moral principles"? 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. Using platform-specific means (e.g. And fwstr > is dereferenced in the following codes. 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. Sonar is ok. 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. A pointer is simply a variable that contains a memory address. I'd guess WG14 has considered these questions, but I haven't until now :). Many platforms can support testing for those also. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. I could've fixed this by changing else to else if (B != null && B.length == 1), but doing so rewards me with warning "condition(B != null && B.length == 1) is always true". PS: I also tried the code in android studio which uses Lint and got no warnings. A bug can cause them never to be reassigned. At this point we define size as strlen(input_str) + 1. Made code more compliant with other rules. 1 Answer Sorted by: 1 Your code is ok. positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature.

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