C# static code analysis: Null pointers should not be dereferenced Small typo nit: "such as if i t pointed to freed memory" meant to say "if it" instead (removing whitespace). The method isNR (minRating) is a helper method that validate among other things, if the object minRating is null public boolean isNR (AgencyRating rating) { return rating == null || isNR (rating.getRatgCaam ()); } When I added the not null validation as sonar suggest. In the code, we check the not nullity with java.util.Objects.nonNull(). I don't need to do this validation again. Connect and share knowledge within a single location that is structured and easy to search. minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). Agreed. What is null pointer exception in android. If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? We really appreciate your help. What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. Many platforms can support testing for those also. Is there a single-word adjective for "having exceptionally strong moral principles"? I added a comment to explain that SIZE_MAX is the limit of size_t. SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. Possible fix: Assign a valid address to the pointer in all branches of the conditional statement.. Pointer can point to dynamically allocated memory. [SONARJAVA-2808] - Jira - SonarSource rev2023.3.3.43278. On many platforms, dereferencing a null pointer results inabnormal program termination, but this is not required by the standard. https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java. If you preorder a special airline meal (e.g. Is the God of a monotheism necessarily omnipotent? Using platform-specific means (e.g. ), 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. java - sonarLint "Null pointers should not be False fault 'Null pointers should not be dereferenced' using Optional Is there a single-word adjective for "having exceptionally strong moral principles"? A NULL pointer can be dereferenced when signatures are being verified on PKCS7 signed or signedAndEnveloped data. 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. What does "Could not find or load main class" mean? My question is; is my solution incorrect? sometimes FP occurs. The same problem we will have with "Add at least one assertion to this test case." A reference to null should never be dereferenced/accessed. How to deal with "java.lang.OutOfMemoryError: Java heap space" error? - the incident has nothing to do with me; can I use this this way? Some Interesting Facts: 1) void pointers cannot be dereferenced. Are there tables of wastage rates for different fruit and veg? 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). But what exactly does it mean to "dereference a null pointer"? Thanks for contributing an answer to Stack Overflow! Find centralized, trusted content and collaborate around the technologies you use most. 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. 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. 4500 Fifth Avenue The alert is related to the sonar rule : Null pointers should not be dereferenced. 1 Answer Sorted by: 1 Your code is ok. How handle the initialization of "responseDto" without "null" because is throwing the issue on sonar. 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. Doing so will cause a NullReferenceException to be thrown. How to tell which packages are held back due to phased updates. That's true. public boolean isNameEmpty() { return getName().length() == 0; // Noncompliant; the result of getName() could be null, but isn't null-checked } . My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? How do you ensure that a red herring doesn't violate Chekhov's gun? What is pointed to should only be deleted if it was created with new. Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. 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. Sonar: Null pointers should not be dereferenced - Stack Overflow How do you ensure that a red herring doesn't violate Chekhov's gun? Extended Description NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions. When and how should I use a ThreadLocal variable? I've changed it to say null pointer instead of invalid pointer. Does it just mean failing to correctly check if a value is null? VB.NET static code analysis: Null pointers should not be dereferenced Whats the grammar of "For those whose stories they are"? http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. But when length of A is 1, the control never reaches the else block. This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. The return value from strchr() is often NULL, but the dev might know that a specific strchr() function call will not return NULL. 3.7. Is there a solution to add special characters from software and how to do it, Acidity of alcohols and basicity of amines. isEmpty(Collection collection) 1. Introduction - Understanding and Using C Pointers [Book] 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 . Automated Detection Null pointer dereferences can happen in path-dependent ways. strongSwan - strongSwan Vulnerability (CVE-2023-26463) And the compliant solution guarantees that the pointer will be valid if the code calls memcpy(). So no checking of the length is necessary (besides preventing integer overflow, which the compliant solution does). In the case of the ARM and XScale architectures, the 0x0 address is mapped in memory and serves as the exception vector table; consequently, dereferencing 0x0 did not cause an abnormal program termination. This noncompliant code example is derived from a real-world example taken from a vulnerable version of the libpng library as deployed on a popular ARM-based cell phone [Jack 2007]. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Sonar violation: Null pointers should not be dereferenced #7459 - GitHub 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. A pointer is simply a variable that contains a memory address. There are other problems with this code, as is noted in the rule. This rule applies to all null pointers, regardless of which function returned them. At best, such an exception will cause abrupt program termination. All content is copyright protected. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. NullPointerException is a RuntimeException. 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 code also violates ERR33-C. Detect and handle standard library errors. the Java one). 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. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? So Bar might not be initialized but then the last line of your example should not be evaluated in this case. Additionally, if input_str is a null pointer, the call to strlen() dereferences a null pointer, also resulting in undefined behavior. Best to cite C11 s7.24.2.1 here: The memcpy function copies n characters from the object pointed to by s2 into the object pointed to by s1. Dereferencing a null pointer results in undefined behavior. Provide a self-contained reproducer (zipped project?) Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. SonarQube null pointers should not be dereferenced on try/catch What is a NullPointerException, and how do I fix it?,What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them? 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. (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). Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. Is there a single-word adjective for "having exceptionally strong moral principles"? Pointers in C Explained - They're Not as Difficult - freeCodeCamp.org Sonar false-positive on rule: Null pointers should not be dereferenced I added an assertion to that compliant code example. 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. See the "Null pointer checks may be optimized away more aggressively" section inhttps://gcc.gnu.org/gcc-4.9/porting_to.htmlas an example with one common implementation. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. For the time being, I would unfortunately recommend to mark as False Positive the issue. 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. Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. NullPointerException is thrown when program attempts to use an object reference that has the null value. can have the value zero on a call to that function. You're in a company-managed project. That interpretation of the standard is not supported universally. 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 . Likewise, pointers to freed memory are not valid. (from res.getBody().getServiceResult() ). Now (sonarqube java analyzer version 4.3.0.7717) it's supported and works fine. Is there a proper earth ground point in this switch box? ucsi->connector gets dereferenced by both ucsi_connector_change() and ucsi_resume(), both check for ucsi->connector being NULL in case ucsi_init() has not finished yet; or in case ucsi_init() has failed. COMP-PROG-MODULE-5-6-REVIEWER.pdf - Pointers to string SonarQube Version 6.7.2 (build 37468) Write a semantic patch to nd cases where the result of calling kmalloc is dereferenced with no previous NULL pointer test. null(java.lang.NullPointerException) . Accessing or modifying a null object's field. Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, SonarQube - Null Pointer Dereference Issue. () Two null pointers will always be equal to each other. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? This will normally lead to an unhandled error, resulting in a segmentation fault. Does Java have support for multiline strings? This solution also ensures that theuser_data pointer is not null. Check whether a String is not Null and not Empty. This is a feature that we are currently heavily working on to be able to switch off such kind of false positives. Depending on whether the pointer is valid (i.e. If copying takes place between objects that overlap, the behavior is undefined. Thanks for contributing an answer to Stack Overflow! [RSPEC-2259] - Jira , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow Recovering from a blunder I made while emailing a professor. Reference vs dereference pointers in arguments C++/C Software project. Why do academics stay as adjuncts for years rather than move around? Rule squid:S2259 is based on a Symbolic Execution (SE) engine. 11 Sep, 2006. raiseException() return, Sonar 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 As for today, the SE engine is able to explore non-overridable methods (static, for instance), when declared in the same file being analyzed. The result of calling such a helper function should be . 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". ncdu: What's going on with this second size column? Recovering from a blunder I made while emailing a professor. Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. SonarJava Version 5.9.2 (build 16552). By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. The null pointer check for writing or dereferencing should be a compiler flag or library setting. 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. 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]. For example the following program doesn't compile. It is still a pointer though, to use it you just have to cast it to another kind of pointer first. Reports. A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. Minimising the environmental effects of my dyson brain. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? Answered: difference between a void pointer and a | bartleby Obviously the value of that pointer could have changed since the . How can we prove that the supernatural or paranormal doesn't exist? Null pointers should not be dereferenced. {"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. Just because something is a pointer does not mean you should call delete . Hi Andreas, Thanks for the feedback. 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. Just a few words about the rule now. Issues Components. 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. Is there a proper earth ground point in this switch box? Asking for help, clarification, or responding to other answers. }. The method isNR(minRating) is a helper method that validate among other things, if the object minRating is null. This topic was automatically closed 7 days after the last reply. Also, the term 'pointer' is bad (but maybe it comes from the FindBugs tool): Java doesn't have pointers, it has references.
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