null pointers should not be dereferenced null pointers should not be dereferenced

Is there a proper earth ground point in this switch box? 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. , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow You can use Optional instead. The return value from strchr() is often NULL, but the dev might know that a specific strchr() function call will not return NULL. 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. Why do academics stay as adjuncts for years rather than move around? But even with this, the concerned object it tagged as a possible NullPointerException problem. Thanks for your relpy. ii. A reference to null should never be dereferenced/accessed. Phew, we're agreed here. But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. null(java.lang.NullPointerException) . Pointer members in structs are not checked. The n=0 is a mildly interesting edge case: Clearly a pointer that points to at least one valid byte could be used as the src or dest pointer to a call to memcpy(, 0). Thanks, David! IMHO, the rule title should be changed to something less general. ssize_t (*aio_read)(struct kiocb *, char __user *, size_t . The standard will simply copy 0 byteswhich is essentially a no-op. Could I capture, and I would be able to glean much security information from the dump? That is why I explicitly check for this in my attempted solution. 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. You need to benchmark. What does it mean that a reference must refer to an object, not a dereferenced null pointer? This likely means that youre on an ancient version of the Java analyzer. 1 Answer Sorted by: 2 Your code needs to do something about the possible NullPointerException when some exception is caught, because in this scenario the responseDto will be null. io.NotSerializableException : java. The 2nd NCCE/CS pair seems redundant with the first NCCE/CS pair. If you preorder a special airline meal (e.g. @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. LANG.MEM.NPDLANG.STRUCT.NTADLANG.STRUCT.UPD, Null pointer dereferenceNull test after dereferenceUnchecked parameter dereference, Can detect violations of this rule. 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. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. Key here (explains table format and definitions), EXP34-C = Union( CWE-690, list) where list =. 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. So you can declare a string t and then add characters to the string with a plus sign : t += 'a'; The code you are having issue with is just moving the pointer to the next character which the foreach is already doing. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? To create a custom null validation method declare an attribute with name ValidatedNotNullAttribute and mark the parameter that is By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Hello. Reports. 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. All content is copyright protected. What is a serialVersionUID and why should I use it? Is a PhD visitor considered as a visiting scholar? But when length of A is 1, the control never reaches the else block. Provide a self-contained reproducer (zipped project?) https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx A NULL pointer can be dereferenced when signatures are being verified on PKCS7 signed or signedAndEnveloped data. Powered by Discourse, best viewed with JavaScript enabled. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? With their flexibility, void pointers also bring some constraints. 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. I would also guess that pointers that point to the one-past-the-end of an array are also invalid. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. Connect and share knowledge within a single location that is structured and easy to search. At worst, it could expose debugging information that would be useful to an attacker, or What does "Could not find or load main class" mean? Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. After that, you call res.getBody() again. which version of SonarQube are you using? can have the value zero on a call to that function. The same problem we will have with "Add at least one assertion to this test case." 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. 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. 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. Then we hit memcpy with length 0. 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. If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. Good question! Such long getter chains can also be replaced with Optional + map + ifPresent lambda style. - the incident has nothing to do with me; can I use this this way? Is it possible to create a concave light? At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . I'd guess null pointers are not valid, even though they point to 0 bytes. 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>. Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. 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. We resolved it by adding our tools path in the white list, and repackaging it. Things go fine now. Does Counterspell prevent from any further spells being cast on a given turn? 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). Share Improve this answer Follow answered Oct 5, 2017 at 16:27 util.regex.Matcher, java - Swing .getParent() . 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. 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. At this point we define size as strlen(input_str) + 1. 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). Are there tables of wastage rates for different fruit and veg? This is indeed a false positive because, at time of writing, the sonarqube java analyzer (version 4.2.1 at time of writing) does not support cross procedural analysis and so it is not able to determine that indeed, for the condition to be true, the value of minRating has to be non null. Correct; a null pointer is not a valid pointer for the C library functions. The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. Software project. It could be non-null the first time but not the second time, sonar does not know this. When exploring such methods, the engine then deduces behaviors regarding null-checking (among other things). It does not point to any area of memory. positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. 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. When I added the not null validation as sonar suggest. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? 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). It also uses the unsigned type size_t to pass the length parameter, ensuring that negative values are not passed to func(). I believe that dereferencing NULL should not crash the system, should not allow a write to a NULL pointer area, but should always set errno, If I am a hacker, could I trap a null failure that would force a memory dump. We really appreciate your help. At best, such an exception will cause abrupt program termination. Find centralized, trusted content and collaborate around the technologies you use most. In the meantime, Im locking this thread. 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 . You can compare a pointer with NULL to test for the special condition. Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. 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. 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. I've changed it to say null pointer instead of invalid pointer. Agreed. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Making statements based on opinion; back them up with references or personal experience. 3.Null pointers should not be derefer enced/accessed. Status: Dormant. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Ticket opened : Thanks a lot for the minimalized reproducer ! 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. In the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. 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. Making statements based on opinion; back them up with references or personal experience. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). 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. Unfortunately, its actual state also has some limitations, like the one you are hitting here. Recovering from a blunder I made while emailing a professor. EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. 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?) Avoid Returning null from Methods. Null pointer should not be dereferenced , So Bar might not be initialized but then the last line of your example should not be evaluated in this case. All rights are expressly reserved. 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. IDE extension that lets you fix coding issues before they exist! uninitialized reference-type class members. The expected result here is solve the issue with sonarqube. To learn more, see our tips on writing great answers. Not the answer you're looking for? What sort of strategies would a medieval military use against a fantasy giant? If you call connect() function, it better do the connection, but failing simply because some ptr is NULL is not good behaviour -- failures should . Please direct comments on this JSR to the Spec Lead (s) Team. Thanks for the feedback. I suppose there is a question of "Is a pointer that points to 0 bytes valid?" (C11, S7.24.2.1). Note that it doesn't know how to check for non-heap, non-stack. I added a comment to explain that SIZE_MAX is the limit of size_t. raiseException() return, Sonar Put a new ResponseEntity is wrong because I won't know what will be the answer for the status of http. This code also violates ERR33-C. Detect and handle standard library errors. Doing so will at best cause abrupt program termination, without the If not, this might be a bug. Just because something is a pointer does not mean you should call delete . Whoops, you're right. Dereferencing a null pointer can lead to a denial of service. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. String *x, y; X is a pointer to a string, Y is a string & = address of variable/ operator || referencing operator * = value of address || dereferencing operator Pointers = stores memory address as its variables NULL pointer = a constant with a value of zero defined || assigned to null Void pointer = a pointer that is not associated with any data types New operator = denotes a request for . In C/C++ speak, 'dereferencing' simply means getting the object that a pointer . context.RaiseException . 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 say "theoretical" because I have not successfully produced strings of this length in testing. 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. Your code needs to do something about the possible NullPointerException when some exception is caught, because in this scenario the responseDto will be null. The correct idiom is to only allocate storage if the pointer is currently NULL. Small typo nit: "such as if i t pointed to freed memory" meant to say "if it" instead (removing whitespace). All content is copyright protected. However there is no portable way to verify that the pointer is valid, other than checking for null. The purpose of a NULL pointer is not to cause a processor exception when it is dereferenced (although that is nice to have for debugging.) Which @NotNull Java annotation should I use? Discover SonarLint SaaS Setup is effortless and analysis is automatic for most languages Discover SonarCloud Self-Hosted Fast, accurate analysis; enterprise scalability Discover SonarQube Secrets ABAP Just a few words about the rule now. Check whether a String is not Null and not Empty. That's true. 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. context.RaiseException , (/) 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. https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java. ), 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. 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(). assert(!invalid(p)); // or whatever, bool invalid(const void *p) { The result of calling such a helper function should be . . As for copy vs pointer/reference - it depends. We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. Dereferencing a null pointer results in undefined behavior. best, such an exception will cause abrupt program termination. {"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. How can this new ban on drag possibly be considered constitutional? ), 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). A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). 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 bypass security measures. The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. 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.