null pointers should not be dereferenced
)}"); 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. 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. in above code, Basically, yes. These can be: Invoking a method from a null object. Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. 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). ncdu: What's going on with this second size column? So we have to check all the arguments before performing any actions. 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://www.yammer.com/ http://feeds.feedburner.com/office/fmNx vegan) just to try it, does this inconvenience the caterers and staff? 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 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" // <------- reported violation: NullPointerException might be thrown as 'bar' is nullable here, https://jira.sonarsource.com/browse/SONARJAVA-1490, https://groups.google.com/d/msgid/sonarqube/4752a999-246e-42c2-bbdc-8a44a5564ce9%40googlegroups.com. specifies the length of the array for a function. The final NCCE is actually more insidious than it seems at first. 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. 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. isEmpty(Map map) 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. Which ensures that the chunkdata pointer is valid, but makes no such check to the user_data pointer. How can we prove that the supernatural or paranormal doesn't exist? 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. Extended Description NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions. 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. Such long getter chains can also be replaced with Optional + map + ifPresent lambda style. Thanks for contributing an answer to Stack Overflow! One could argue that all code examples would be redundant with the first pair. What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Should trycatch go inside or outside a loop? 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. Thanks for the feedback. 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. To learn more, see our tips on writing great answers. Essentially, this code and the previous dereference disagree as to whether this value is allowed to be null. Hello. Does Counterspell prevent from any further spells being cast on a given turn? How can I check before my flight that the cloud separation requirements in VFR flight rules are met? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. But no where in that particular idiom would a NULL pointer necessarily be deferenced. Could I capture, and I would be able to glean much security information from the dump? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Your assertion is not backed by the wording in the standard, nor by common implementer understanding. 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. For the time being, I would unfortunately recommend to mark as False Positive the issue. Unlike reference types, pointer types are not tracked by the default garbage . There are many ways to resolve this. False-positives are pointed out in other SO posts (1 & 2), where nulls are involved across functions and procedures. I believe in this case, either expression would work. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? Is there a single-word adjective for "having exceptionally strong moral principles"? https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java. In C/C++ speak, 'dereferencing' simply means getting the object that a pointer . Finally, there is the matter of the compliant solution. http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. All content is copyright protected. Reports. 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. Now, you can find the list of whitelisted methods here. ability to run any cleanup processes. The idea is not to guarantee validity, but to catch a substantial number of problems that could occur. Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. Interactions/interfaces with C can't use references. Rule squid:S2259 is based on a Symbolic Execution (SE) engine. SonarQube Version 6.7.2 (build 37468) can have the value zero on a call to that function. positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". Accessing or modifying a null object's field. minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). Dereferencing > this null pointer may cause the kernel go wrong. sonarlint complains that It also adds assertions to document that certain other pointers must not be 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.) By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. To learn more, see our tips on writing great answers. What is pointed to should only be deleted if it was created with new. In Java, a special null value can be assigned to an object reference. Trying to understand how to get this basic Fourier Series. That is why I explicitly check for this in my attempted solution. When and how should I use a ThreadLocal variable? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. 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. Which @NotNull Java annotation should I use? Can you please start a new thread and be more explicit about the issue you are observing. You can use Optional instead. It does not point to any area of memory. The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. Not the answer you're looking for? Passing ownership of something also requires pointers. , NPE : null-, . Agreed. SonarJava Version 5.9.2 (build 16552). Please explain: Without this, we wont be able to help you. 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 */ This sounds indeed like a bug in the flow when an exception is raised. > Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to > the caller site. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. IMHO, the rule title should be changed to something less general. 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 2nd NCCE/CS pair seems redundant with the first NCCE/CS pair. Thanks for your relpy. That's true. "After the incident", I started to be more careful not to trip over things. This rule applies to all null pointers, regardless of which function returned them. NULL vs Void Pointer - Null pointer is a value, while void pointer is a type. Null pointer should not be dereferenced , Much like dereferencing a dangling (or wild) pointer leads to undefined behavior, dereferencing a null pointer also leads to undefined behavior. We. This issues is displayed by SonarQube. ), 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. () 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. New replies are no longer allowed. positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. Is there a proper earth ground point in this switch box? Do "superinfinite" sets exist? 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 it possible to create a concave light? Possible fix: Assign a valid address to the pointer in all branches of the conditional statement.. Pointer can point to dynamically allocated memory. SonarJava. that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). Im very new to sonar, is there a way to add methods to the whitelist? A pointer to null (the 0 memory address) should never be dereferenced/accessed. 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. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? 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. 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. Then we hit memcpy with length 0. Recovering from a blunder I made while emailing a professor. Trying to understand how to get this basic Fourier Series. Find centralized, trusted content and collaborate around the technologies you use most. This code also violates ERR33-C. Detect and handle standard library errors. But what exactly does it mean to "dereference a null pointer"? In some situations, however, dereferencing a null pointer can lead to the execution of arbitrary code [Jack 2007,van Sprundel 2006]. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? java Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. I would also guess that pointers that point to the one-past-the-end of an array are also invalid. That makes sense. Identify where the allocation occurs. SonarQube - Null Pointer Dereference Issue java simonsirak (Simon Sirak) June 14, 2018, 1:18pm 1 Hi! When length is zero, it is probably unusable condition for this function. It is still a pointer though, to use it you just have to cast it to another kind of pointer first. Things go fine now. 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. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Thanks, David! What sort of strategies would a medieval military use against a fantasy giant? 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. In multithreaded programs, null pointer dereferences can violate cache coherency policies and can cause resource leaks. A reference to null should never be dereferenced/accessed. PS: I also tried the code in android studio which uses Lint and got no warnings. Find centralized, trusted content and collaborate around the technologies you use most. SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. very old code or C code being worked into c++ may have functions that expect the user to delete the data. I've changed it to say null pointer instead of invalid pointer. For example the following program doesn't compile. Instead use String.valueOf (object). ncdu: What's going on with this second size column? When c_str is dereferenced in memcpy(), the program exhibits undefined behavior. All content is copyright protected. , . To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. which version of SonarQube are you using? Sonar is ok. Sonar can't determine that the helper method did the null validation. Styling contours by colour and by line thickness in QGIS. When B is null, The control reaches inside the main if block only when length of A is 1. 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). A reference to null should never be dereferenced/accessed. I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. 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 . This engine is validating execution paths and checking for non-null values or null-check along the way, exploring all the possibilities. How do I align things in the following tabular environment? This code also violates ERR33-C. Detect and handle standard library errors. Powered by Discourse, best viewed with JavaScript enabled. The fact that you can't pass a null (no object) with a reference parameter can be a reason to use a pointer instead. And fwstr > is dereferenced in the following codes. Explain about call by reference with an . 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]. The expected result here is solve the issue with sonarqube. Check whether a String is not Null and not Empty. 11 Sep, 2006. On the command prompt, the same arguments work and the record is added in db but not when I call the stored procedure from inside java program CallableStatement insertStat = db_conn.prepareCall (" {call InsertCourses (?,?,?,?,?,?,?,? Search for vulnerabilities resulting from the violation of this rule on the CERT website. 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. LANG.MEM.NPDLANG.STRUCT.NTADLANG.STRUCT.UPD, Null pointer dereferenceNull test after dereferenceUnchecked parameter dereference, Can detect violations of this rule. We resolved it by adding our tools path in the white list, and repackaging it. Doing so will cause a NullReferenceException to be thrown. In C, dereferencing a null pointer is undefined behavior. Making statements based on opinion; back them up with references or personal experience. This solution also ensures that theuser_data pointer is not null. Doing so will cause a NullPointerException to be thrown. rev2023.3.3.43278. Does Java have support for multiline strings? It's a modular system with the . Depending on whether the pointer is valid (i.e. I'd guess null pointers are not valid, even though they point to 0 bytes. Null pointers should not be dereferenced. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Sonar: Null pointers should not be dereferenced, Why should Java 8's Optional not be used in arguments, Sonar alert : "private" methods that don't access instance data should be "static", sonarLint complains "Null pointers should not be dereferenced (squid:S2259)" despite that possibility being handled, Java: (false?) Just a few words about the rule now. At best, such an exception will cause abrupt program termination. I already tried to put ResponseEntity
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