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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. Connect and share knowledge within a single location that is structured and easy to search. Agreed. // <------- 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. 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. 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. NULL vs Uninitialized pointer - An uninitialized pointer stores an undefined value. This solution also ensures that theuser_data pointer is not null. Find centralized, trusted content and collaborate around the technologies you use most. Finally, there is the matter of the compliant solution. What is the point of Thrower's Bandolier? How do I align things in the following tabular environment? I have a sonar alert on this call minRating.getRatgCaam(). 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. 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. Accessing or modifying a null object's field. 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. sonarqube 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. Appropriate typecasting is necessary. rev2023.3.3.43278. I reordered that code example to do all the checks before allocations. 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. Check whether a String is not Null and not Empty. A reference to Nothing should never be dereferenced/accessed. 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". The null pointer check for writing or dereferencing should be a compiler flag or library setting. return p == NULL || (char *)p < &_etext; 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. When B is null, The control reaches inside the main if block only when length of A is 1. Calls to extension methods are not reported because they can still operate on null values. If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. Now (sonarqube java analyzer version 4.3.0.7717) it's supported and works fine. Not the answer you're looking for? 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. 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). (from res.getBody().getServiceResult() ). When a variable is declared as being a pointer to type void, it is known as a generic pointer. This sounds indeed like a bug in the flow when an exception is raised. ability to run any cleanup processes. 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. This is a matter of style, and also following code walkthrough. This likely means that youre on an ancient version of the Java analyzer. I added a comment to explain that SIZE_MAX is the limit of size_t. extern char _etext; Asking for help, clarification, or responding to other answers. Why do academics stay as adjuncts for years rather than move around? This code also violates ERR33-C. Detect and handle standard library errors. The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. This is a feature that we are currently heavily working on to be able to switch off such kind of false positives. Making statements based on opinion; back them up with references or personal experience. But passing 0 to memcpy() is not one of them. 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. Java Specification Participation Agreement version in use: 2.0. () 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. The user_data pointer could be invalid in other ways, such as pointing to freed memory. I believe in this case, either expression would work. So we have to check all the arguments before performing any actions. For the time being, I would unfortunately recommend to mark as False Positive the issue. How to tell which packages are held back due to phased updates. . The alert is related to the sonar rule : Null pointers should not be dereferenced. The null concept refers to the idea that a pointer can hold a special value that is not equal to another pointer. Pittsburgh, PA 15213-2612 One could argue that all code examples would be redundant with the first pair. You're in a company-managed project. 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. Status: Dormant. And the semantics, as I said, are different. Rule squid:S2259 is based on a Symbolic Execution (SE) engine. What is null pointer exception in android. )}"); Which ensures that the chunkdata pointer is valid, but makes no such check to the user_data pointer. That is only true if possibleNumbers contains no element.. BTW: none of these warnings are shown by . That is, sets equivalent to a proper subset via an all-structure-preserving bijection. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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). Your code needs to do something about the possible NullPointerException when some exception is caught, because in this scenario the responseDto will be null. It could be non-null the first time but not the second time, sonar does not know this. Now, you can find the list of whitelisted methods here. Software project. 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). You can use Optional instead. All rights are expressly reserved. Whats the grammar of "For those whose stories they are"? Is there a single-word adjective for "having exceptionally strong moral principles"? When exploring such methods, the engine then deduces behaviors regarding null-checking (among other things). But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. Automated Detection Null pointer dereferences can happen in path-dependent ways. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? The correct idiom is to only allocate storage if the pointer is currently NULL. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. LANG.MEM.NPDLANG.STRUCT.NTADLANG.STRUCT.UPD, Null pointer dereferenceNull test after dereferenceUnchecked parameter dereference, Can detect violations of this rule. I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. it could allow an attacker to bypass security measures. Asking for help, clarification, or responding to other answers. Just a few words about the rule now. 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. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". If you try to access any member variables or methods with that variable, you are trying to dereference it. very old code or C code being worked into c++ may have functions that expect the user to delete the data. 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 */ sonarLint (3.2.) A NULL pointer can be dereferenced when signatures are being verified on PKCS7 signed or signedAndEnveloped data. 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} Dereferencing > this null pointer may cause the kernel go wrong. (C11, S7.24.2.1). How to use Slater Type Orbitals as a basis functions in matrix method correctly? At best, such an exception will cause abrupt program termination. Doing so will cause a NullReferenceException to be thrown. But what exactly does it mean to "dereference a null pointer"? Connect and share knowledge within a single location that is structured and easy to search. Can you please start a new thread and be more explicit about the issue you are observing. And fwstr > is dereferenced in the following codes. On many platforms, dereferencing a null pointer results in abnormal program termination, but this is not required by the standard. validated for null in your method declaration with it: 2008-2023 SonarSource S.A., Switzerland. Shouldn't the function check all pointers before dereferencing them or passing them to another function? 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.