Made code more compliant with other rules. "After the incident", I started to be more careful not to trip over things. On many platforms, dereferencing a null pointer results inabnormal program termination, but this is not required by the standard. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. // <------- 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. Likewise, pointers to freed memory are not valid. Correct; a null pointer is not a valid pointer for the C library functions. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. As for copy vs pointer/reference - it depends. 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. Using Kolmogorov complexity to measure difficulty of problems? Thanks, David! https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx You're in a company-managed project. 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. very old code or C code being worked into c++ may have functions that expect the user to delete the data. 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. 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. Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. Things go fine now. How do I align things in the following tabular environment? Now, you can find the list of whitelisted methods here. 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. At worst, it could expose debugging information that would be useful to an attacker or it could allow an It means this is illegal: T* p = nullptr; T& r = *p; // illegal NOTE: Please do not email us saying the above works on your particular version of your particular compiler. Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. raiseException() return, Sonar uninitialized reference-type class members. positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. That is only true if possibleNumbers contains no element.. BTW: none of these warnings are shown by . Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. As for today, the SE engine is able to explore non-overridable methods (static, for instance), when declared in the same file being analyzed. Doing so will cause a NullReferenceException to be thrown. Software Engineering Institute
The issue arises when dereferenced pointers are used. Is there a single-word adjective for "having exceptionally strong moral principles"? We. 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). To learn more, see our tips on writing great answers. 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. This is a feature that we are currently heavily working on to be able to switch off such kind of false positives. Thank you for clarifying your assertion until I understood it properly. Sonar is ok. Mutually exclusive execution using std::atomic? That makes sense. I've changed it to say null pointer instead of invalid pointer. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. I'd guess null pointers are not valid, even though they point to 0 bytes. Some Interesting Facts: 1) void pointers cannot be dereferenced. If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. Do "superinfinite" sets exist? This will normally lead to an unhandled error, resulting in a segmentation fault. IDE extension that lets you fix coding issues before they exist! The null pointer check for writing or dereferencing should be a compiler flag or library setting. Java Specification Participation Agreement version in use: 2.0. There is no legitimate reason to dereference a null pointer unless you on a rare system that maps page zero (or you intend your program to crash). What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. How do you ensure that a red herring doesn't violate Chekhov's gun? Not the answer you're looking for? If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Using Kolmogorov complexity to measure difficulty of problems? 1 Answer Sorted by: 1 Your code is ok. We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. }. It also adds assertions to document that certain other pointers must not be null. In C# and Java, all reference types can point to null. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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(). https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java. Doing so will cause a NullReferenceException to be thrown. Minimising the environmental effects of my dyson brain. There are many ways to resolve this. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Trying to understand how to get this basic Fourier Series. sometimes FP occurs. ", Eclipse - Sonar S2629 possible false positive with new String, SonarQube null pointers should not be dereferenced on try/catch, getTextContent() through "Null pointers should not be dereferenced". It could be non-null the first time but not the second time, sonar does not know this. How do I align things in the following tabular environment? Sonar is ok. Sonar can't determine that the helper method did the null validation. It's still illegal. The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. In my experience, there are reasons to check for a NULL pointer other than dereferencing it. . The problem is that something like %*pbl which reads a bitmask, will save the pointer to the bitmask in the buffer. The idea is not to guarantee validity, but to catch a substantial number of problems that could occur. Doing so will at best cause abrupt program termination, without the It's a modular system with the . 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. Issues Components. If malloc() fails, it returns a null pointer that is assigned to c_str. context.RaiseException . In C, dereferencing a null pointer is undefined behavior. The same problem we will have with "Add at least one assertion to this test case." Now (sonarqube java analyzer version 4.3.0.7717) it's supported and works fine. Is the God of a monotheism necessarily omnipotent? Key here (explains table format and definitions), EXP34-C = Union( CWE-690, list) where list =. This sounds indeed like a bug in the flow when an exception is raised. Does Java have support for multiline strings? the Java one). All rights are expressly reserved. NullPointerException is thrown when program attempts to use an object reference that has the null value. New replies are no longer allowed. ), 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). In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. 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. The result of calling such a helper function should be . 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. Passing ownership of something also requires pointers. I suppose there is a question of "Is a pointer that points to 0 bytes valid?" In the meantime, Im locking this thread. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. I added a comment to explain that SIZE_MAX is the limit of size_t. 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. In some situations, however, dereferencing a null pointer can lead to the execution of arbitrary code [Jack 2007,van Sprundel 2006]. A reference to null should never be dereferenced/accessed. We cannot understand how there could be a null pointer exception at the reported line. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. These can be: Invoking a method from a null object. Unfortunately the problem is much more complex, and generally unsolvable within standard C. Consider the following example: There's no way f can check whether x points into valid memory or not. Im very new to sonar, is there a way to add methods to the whitelist? I'd guess WG14 has considered these questions, but I haven't until now :). 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. 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. Recovering from a blunder I made while emailing a professor. 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. I think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. . You need to benchmark. At worst, it could expose debugging information that would be useful to an attacker, or sonar-java. This is indeed an obvious False Positive from the rule. 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. > Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to > the caller site. Using platform-specific means (e.g. A NULL pointer can be dereferenced when signatures are being verified on PKCS7 signed or signedAndEnveloped data. [4] Can you please start a new thread and be more explicit about the issue you are observing. (in the meantime, in case of any other false-positive suspicion, make sure to check those latest versions as bunch of improvements are regularly released). The final NCCE is actually more insidious than it seems at first. can have the value zero on a call to that function. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. (/). A bug can cause them never to be reassigned. Check whether a String is not Null and not Empty. Hello. When B is null, The control reaches inside the main if block only when length of A is 1. Seems the analizer don't recognice the logic with the funcional object Optional. context.RaiseException , (/) Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. ssize_t (*aio_read)(struct kiocb *, char __user *, size_t . Dereferencing a null pointer results in undefined behavior. However there is no portable way to verify that the pointer is valid, other than checking for null. Im currently using SonarQube version 5.6.6. better way to handle this is to store the result of method invocation in a variable. I believe in this case, either expression would work. Just a few words about the rule now. This is a matter of style, and also following code walkthrough. Asking for help, clarification, or responding to other answers. Could I capture, and I would be able to glean much security information from the dump? Then we hit memcpy with length 0. You're in a company-managed project. Pointer members in structs are not checked. Possible fix: Assign a valid address to the pointer in all branches of the conditional statement.. Pointer can point to dynamically allocated memory. Im having trouble understanding your problem. SonarJava Version 5.9.2 (build 16552). What is a NullPointerException, and how do I fix it?,What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them? Much like dereferencing a dangling (or wild) pointer leads to undefined behavior, dereferencing a null pointer also leads to undefined behavior. . vegan) just to try it, does this inconvenience the caterers and staff? The solution that I recommend is not work with null returns or variables on Java, try to avoid it. 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). return p == NULL || (char *)p < &_etext; What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? Basically, yes. Goal Can I tell police to wait and call a lawyer when served with a search warrant? 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Calls to extension methods are not reported because they can still operate on null values. 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 subscribe to this RSS feed, copy and paste this URL into your RSS reader. In C/C++ speak, 'dereferencing' simply means getting the object that a pointer . (I think you cover that in a different rule.) sonarlint, sonarLint (3.2.) Does a summoned creature play immediately after being summoned by a ready action? 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. If you preorder a special airline meal (e.g. So, this code should address the Sonar problem: You can also eliminate the null check using Optional>, like: Even I don't recommend this, you can just check the null responseDto without any use of Optional: Thanks for contributing an answer to Stack Overflow! 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. http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. Currently I'm working with SonarQube solving issues but I'm facing a trouble to how handle null pointers that shouldn't be dereferenced. Trying to understand how to get this basic Fourier Series. Null pointers should not be dereferenced. isEmpty(Map map) And if there is no pointer_default declaration, then the default default is ref. If that variable hasn't had a reference assigned, it's a null reference, which (for internal/historical reasons) is referred to as a null pointer. The user_data pointer could be invalid in other ways, such as pointing to freed memory. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. False-positives are pointed out in other SO posts (1 & 2), where nulls are involved across functions and procedures. A reference to Nothing should never be dereferenced/accessed. At best, such an exception will cause abrupt program termination. 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. Should trycatch go inside or outside a loop? 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 . Software project. Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, SonarQube - Null Pointer Dereference Issue. 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. The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. Styling contours by colour and by line thickness in QGIS. {"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. Is there a single-word adjective for "having exceptionally strong moral principles"? 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 (?,?,?,?,?,?,?,? 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. How can we prove that the supernatural or paranormal doesn't exist? Is there a proper earth ground point in this switch box? 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} 3.Null pointers should not be derefer enced/accessed. 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. To learn more, see our tips on writing great answers. 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. This compliant solution ensures that the pointer returned by png_malloc() is not null. In the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. What is null pointer exception in android. My below code where I'm calling a stored procedure is giving a null pointer exception. ), 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. Which @NotNull Java annotation should I use? What sort of strategies would a medieval military use against a fantasy giant? When exploring such methods, the engine then deduces behaviors regarding null-checking (among other things). Status: Dormant. void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. Coverity Prevent cannot discover all violations of this rule, so further verification is necessary, Detects when NULL is dereferenced (Array of pointers is not checked. 4. Also, the term 'pointer' is bad (but maybe it comes from the FindBugs tool): Java doesn't have pointers, it has references. Put a new ResponseEntity is wrong because I won't know what will be the answer for the status of http. Is there a proper earth ground point in this switch box? Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? That interpretation of the standard is not supported universally. This compliant solution eliminates the null pointer deference by initializing sk to tun->sk following the null pointer check. Just because something is a pointer does not mean you should call delete . 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. SonarQube Version 6.7.2 (build 37468) Recovering from a blunder I made while emailing a professor. Ah, gotcha. specifies the length of the array for a function. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. How to tell which packages are held back due to phased updates. Rule squid:S2259 is based on a Symbolic Execution (SE) engine. Asking for help, clarification, or responding to other answers. Not the answer you're looking for? 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. To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. But when length of A is 1, the control never reaches the else block. Can I tell police to wait and call a lawyer when served with a search warrant? Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). Many platforms can support testing for those also. What is a serialVersionUID and why should I use it? 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.. At best, such an exception will cause abrupt program termination. When a variable is declared as being a pointer to type void, it is known as a generic pointer. 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. . Unfortunately, its actual state also has some limitations, like the one you are hitting here. in above code, We can see that at obj.run(), obj can not be null, but is pointed out by Sonar. This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. (In contrast, the case of passing 0 bytes to malloc is addressed in C11.)
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