Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Connect and share knowledge within a single location that is structured and easy to search. }. 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. But no where in that particular idiom would a NULL pointer necessarily be deferenced. The return value from strchr() is often NULL, but the dev might know that a specific strchr() function call will not return NULL. Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. Carnegie Mellon University
To subscribe to this RSS feed, copy and paste this URL into your RSS reader. When a variable is declared as being a pointer to type void, it is known as a generic pointer. I believe in this case, either expression would work. Find centralized, trusted content and collaborate around the technologies you use most. Thanks, David! Solution 1, it looks like, today's solution tomorrow's problem. 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. And fwstr > is dereferenced in the following codes. Software Engineering Institute
Why is there a voltage on my HDMI and coaxial cables? Finally, there is the matter of the compliant solution. 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. 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. I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. This is a feature that we are currently heavily working on to be able to switch off such kind of false positives. IDE extension that lets you fix coding issues before they exist! return p == NULL || (char *)p < &_etext; isEmpty(Collection collection) Dereferencing a null pointer results in undefined behavior. I added a comment to explain that SIZE_MAX is the limit of size_t. 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. Thus we should check > this kstrdup() operation. A value is checked here to see whether it is null, but this value can't be null because it was previously dereferenced and if it were null a null pointer exception would have occurred at the earlier dereference. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. A reference to null should never be dereferenced/accessed. Dereferencing a null pointer can lead to a denial of service. Off by one error: It is the third example. Java Specification Participation Agreement version in use: 2.0. sonarlint, sonarLint (3.2.) We cannot understand how there could be a null pointer exception at the reported line. 2008-2023 SonarSource S.A., Switzerland. A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). The standard will simply copy 0 byteswhich is essentially a no-op. That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. At worst, it could expose debugging information that would be useful to an attacker or it could allow an When length is zero, it is probably unusable condition for this function. validated for null in your method declaration with it: 2008-2023 SonarSource S.A., Switzerland. Appropriate typecasting is necessary. So let me be more precise in my wording: I assert that a platform whose memcpy() did anything besides copy zero bytes when given n=0 and valid src and dest pointers was not C-standards-compliant. A bug can cause them never to be reassigned. I would also guess that pointers that point to the one-past-the-end of an array are also invalid. My main problem is because I'm doing a restTemplate.exchange with try-catch and declaring a variable with null value before the clause try and then using it inside the try. To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. @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. 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. Accessing or modifying a null object's field. It is useful to have a function with portable interface but platform-dependent implementation: extern bool invalid(const void *); Is null check needed before calling instanceof? int changed to size_t and if size_t parameter's is zero, allocate one word. To learn more, see our tips on writing great answers. void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. When B is null, The control reaches inside the main if block only when length of A is 1. () There are many ways to resolve this. But when length of A is 1, the control never reaches the else block. uninitialized reference-type class members. 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. It could be non-null the first time but not the second time, sonar does not know this. The method isNR(minRating) is a helper method that validate among other things, if the object minRating is null. 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. What is the point of Thrower's Bandolier? 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.. However there is no portable way to verify that the pointer is valid, other than checking for 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. Is there a single-word adjective for "having exceptionally strong moral principles"? What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? NULL vs Void Pointer - Null pointer is a value, while void pointer is a type. This compliant solution eliminates the null pointer deference by initializing sk to tun->sk following the null pointer check. Thank you for clarifying your assertion until I understood it properly. We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. Just because something is a pointer does not mean you should call delete . Sonar is ok. Share Improve this answer Follow answered Oct 5, 2017 at 16:27 How do I align things in the following tabular environment? 1 Answer Sorted by: 1 Your code is ok. Basically, yes. ), 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). 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. (/). For the time being, I would unfortunately recommend to mark as False Positive the issue. That is, sets equivalent to a proper subset via an all-structure-preserving bijection. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. context.RaiseException . The result of calling such a helper function should be . After that, you call res.getBody() again. Agreed. Some Interesting Facts: 1) void pointers cannot be dereferenced. name result . 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. If you call connect() function, it better do the connection, but failing simply because some ptr is NULL is not good behaviour -- failures should . isEmpty(Map map) Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, SonarQube - Null Pointer Dereference Issue. Things go fine now. Does Counterspell prevent from any further spells being cast on a given turn? Making statements based on opinion; back them up with references or personal experience. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? 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). Essentially, this code and the previous dereference disagree as to whether this value is allowed to be null. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. Phew, we're agreed here. which would allow us to systematically observe what you are having. 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. To learn more, see our tips on writing great answers. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. ncdu: What's going on with this second size column? Hi @Michael! SonarJava. In my experience, there are reasons to check for a NULL pointer other than dereferencing it. To learn more, see our tips on writing great answers. Revert Update S2259: "Null pointer dereference" CFG should ignore expressions in Debug.Assert #397 Introduce means to not raise "Expression always true/false" on values that were checked with Debug.Assert. Styling contours by colour and by line thickness in QGIS. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. Isn't easier just to check valid range of length? This compliant solution ensures that the pointer returned by png_malloc() is not null. How do I align things in the following tabular environment? versions used (SonarQube, Scanner, language analyzer) sonarLint (3.2.) 3.7. Hello. 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. This sounds indeed like a bug in the flow when an exception is raised. This topic was automatically closed 7 days after the last reply. 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. 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Batch split images vertically in half, sequentially numbering the output files, Difficulties with estimation of epsilon-delta limit proof, Minimising the environmental effects of my dyson brain. 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. 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. By explicitly teaching the C++ standard class behaviors we can make the Analyzer to find more bugs related to modern C++ code. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. You can compare a pointer with NULL to test for the special condition. So, this code should address the Sonar problem: You can also eliminate the null check using Optional
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