null pointers should not be dereferenced

positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". 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. 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. NULL vs Uninitialized pointer - An uninitialized pointer stores an undefined value. At best, such an exception will cause abrupt program termination. The 2nd NCCE/CS pair seems redundant with the first NCCE/CS pair. We cannot understand how there could be a null pointer exception at the reported line. Do "superinfinite" sets exist? NULL vs Void Pointer - Null pointer is a value, while void pointer is a type. Accessing or modifying a null object's field. EXP34-C. Do not dereference null pointers - Confluence assert(!invalid(p)); // or whatever, bool invalid(const void *p) { (I think you cover that in a different rule.) My question is; is my solution incorrect? 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. The result of calling such a helper function should be . HTTP request redirections should not be open to forging attacks Deserialization should not be vulnerable to injection attacks Endpoints should not be vulnerable to reflected cross-site scripting (XSS) attacks "CoSetProxyBlanket" and "CoInitializeSecurity" should not be used Database queries should not be vulnerable to injection attacks Cause we need throw our own Runtime Exception, well-known methods wont help. In my experience, there are reasons to check for a NULL pointer other than dereferencing it. If you preorder a special airline meal (e.g. Null Pointer Likewise, pointers to freed memory are not valid. Optimizers are optimizing based on this latitude and have been for years. Fix S2583/S2589 FP: On null check if instance is used in try block - GitHub At worst, it could expose debugging information that would be useful to an attacker, or Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Additionally, if input_str is a null pointer, the call to strlen() dereferences a null pointer, also resulting in undefined behavior. I believe in this case, either expression would work. Interactions/interfaces with C can't use references. Please explain: Without this, we wont be able to help you. https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java. Dereferencing a null pointer results in undefined behavior. The only potential null is the return value of list(). Find centralized, trusted content and collaborate around the technologies you use most. The issue arises when dereferenced pointers are used. I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. ", 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". 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 EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. These can be: Invoking a method from a null object. 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. Null pointer - Wikipedia Not the answer you're looking for? 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?) 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. This rule applies to all null pointers, regardless of which function returned them. 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. Making statements based on opinion; back them up with references or personal experience. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Is there a proper earth ground point in this switch box? Why pointers are not used in python? Explained by Sharing Culture [PATCH] drm_edid-load: Fix a missing-check bug in drivers/gpu/drm/drm 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. > Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to > the caller site. It is still a pointer though, to use it you just have to cast it to another kind of pointer first. 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. This solution also ensures that theuser_data pointer is not null. Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? Trying to understand how to get this basic Fourier Series. Seems the analizer don't recognice the logic with the funcional object Optional. rev2023.3.3.43278. But when length of A is 1, the control never reaches the else block. 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. Doing so will cause a NullPointerException to be thrown. Obviously the value of that pointer could have changed since the . very old code or C code being worked into c++ may have functions that expect the user to delete the data. Null Dereference | OWASP Foundation 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 particular, ROSE ensures that any pointer returned by malloc(), calloc(), or realloc() is first checked for NULL before being used (otherwise, it is free()-ed). See C17 7.1.4p1, which says, in part: Each of the following statements applies unless explicitly stated otherwise in the detailed descriptions that follow: 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 pointerto 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. Why do academics stay as adjuncts for years rather than move around? At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . SonarQube - Null Pointer Dereference Issue - Sonar Community java - sonarLint "Null pointers should not be {"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. Two null pointers will always be equal to each other. it could allow an attacker to bypass security measures. The return value from strchr() is often NULL, but the dev might know that a specific strchr() function call will not return NULL. 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. 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]. Recovering from a blunder I made while emailing a professor. Can I tell police to wait and call a lawyer when served with a search warrant? Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. rev2023.3.3.43278. Software project. Styling contours by colour and by line thickness in QGIS. I suppose there is a question of "Is a pointer that points to 0 bytes valid?" We. In the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. [PATCH 1/3] usb: ucsi: Fix NULL pointer deref in ucsi_connector_change() 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. [RSPEC-2259] - Jira To learn more, see our tips on writing great answers. 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. C static code analysis: Null pointers should not be dereferenced C static code analysis Unique rules to find Bugs, Vulnerabilities, Security Hotspots, and Code Smells in your C code All rules 311 Vulnerability 13 Bug 74 Security Hotspot 18 Code Smell 206 Quick Fix 14 Tags "memset" should not be used to delete sensitive data Vulnerability Find centralized, trusted content and collaborate around the technologies you use most. Then the reading of the buffer via bstr_printf() will then look at the pointer to process the final output. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. C# static code analysis: HTTP responses should not be vulnerable to 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. What sort of strategies would a medieval military use against a fantasy giant? In the code, we check the not nullity with java.util.Objects.nonNull(). How can we prove that the supernatural or paranormal doesn't exist? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. C# static code analysis: Null pointers should not be dereferenced 9.7 Null pointers - Learn C++ - LearnCpp.com What is the point of Thrower's Bandolier? parsing /proc/self/maps under linux) one might find out whether the pointer points into mapped memory, but this is still not a guarantee of validity because it is very coarse-grained see again the above example. All content is copyright protected. Is a PhD visitor considered as a visiting scholar? name result . I think that checking for user_data being NULL would be an improvement to the CS so long as there is an explicit mention that user_data being NULL is invalid even if length == 0. I suppose we can check that that is not null, but we cannot check that it is valid (in any portable way). Asking for help, clarification, or responding to other answers. [squid:S2259] False positive - "Null pointers should not be dereferenced" Reports. If copying takes place between objects that overlap, the behavior is undefined. context.RaiseException . You do not have permission to delete messages in this group, Either email addresses are anonymous for this group or you need the view member email addresses permission to view the original message. If you try to access any member variables or methods with that variable, you are trying to dereference it. How do you ensure that a red herring doesn't violate Chekhov's gun? I say "theoretical" because I have not successfully produced strings of this length in testing. java The solution that I recommend is not work with null returns or variables on Java, try to avoid it. , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow Pointers in C Explained - They're Not as Difficult - freeCodeCamp.org But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. Mutually exclusive execution using std::atomic? util.regex.Matcher, java - Swing .getParent() . It does not point to any area of memory. So we have to check all the arguments before performing any actions. How to avoid dereferencing null pointers in Java - Quora Now, you can find the list of whitelisted methods here. The correct idiom is to only allocate storage if the pointer is currently NULL. 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(). void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. It also adds assertions to document that certain other pointers must not be null. It is useful to have a function with portable interface but platform-dependent implementation: extern bool invalid(const void *); 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 . How can this new ban on drag possibly be considered constitutional? Doing so will at best cause abrupt program termination, without the Null pointers should not be dereferenced. I have checked on multiple . that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. In C, dereferencing a null pointer is undefined behavior. Agreed. 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. All rights are expressly reserved. Sonar is ok. Sonar can't determine that the helper method did the null validation. 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. PDF Fourth Coccinelle Workshop { Exercises When and how should I use a ThreadLocal variable? When and how should I use a ThreadLocal variable? This compliant solution eliminates the null pointer deference by initializing sk to tun->sk following the null pointer check. Software project. C# static code analysis: Null pointers should not be dereferenced Products In-IDE IDE extension that lets you fix coding issues before they exist! What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Correct; a null pointer is not a valid pointer for the C library functions. However, memory allocation > functions such as kstrdup() may fail and returns NULL. What is null pointer exception in android Smartadm.ru Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? When B is null, The control reaches inside the main if block only when length of A is 1. The expected result here is solve the issue with sonarqube. There is a missing check for the return value from . Is it possible to rotate a window 90 degrees if it has the same length and width? 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. EXP01-J. Do not use a null in a case where an object is required SonarJava Version 5.9.2 (build 16552). 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. Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Thanks for the feedback. What does it mean that a reference must refer to an object, not a dereferenced null pointer? My below code where I'm calling a stored procedure is giving a null pointer exception. Its purpose is to serve as a special value for a pointer that could indicate a special condition in your program. U1 merged - It is a great text book for learning about linux devices. New replies are no longer allowed. squid:S2259 : A "NullPointerException" could be thrown; "dc" is SonarQube null pointers should not be dereferenced on try/catch, Sonarcube :Null pointers should not be dereferenced, How do you get out of a corner when plotting yourself into a corner. Connect and share knowledge within a single location that is structured and easy to search. 1. Introduction - Understanding and Using C Pointers [Book] When should pointers be checked for NULL in C? 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. Null - But even with this, the concerned object it tagged as a possible NullPointerException problem. Should trycatch go inside or outside a loop? 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. attacker to bypass security measures. Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". What should you do if somebody passes a null pointer for a parameter Finally, there is the matter of the compliant solution. Recovering from a blunder I made while emailing a professor. 4. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? Asking for help, clarification, or responding to other answers. Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. 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. The indicated severity is for this more severe case; on platforms where it is not possible to exploit a null pointer dereference to execute arbitrary code, the actual severity is low. ncdu: What's going on with this second size column? Made code more compliant with other rules. I'd guess null pointers are not valid, even though they point to 0 bytes. 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. How to use java.net.URLConnection to fire and handle HTTP requests, Why should Java 8's Optional not be used in arguments, sonarLint complains "Null pointers should not be dereferenced (squid:S2259)" despite that possibility being handled. When you have a variable of non-primitive type, it is a reference to an object. 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". All content is copyright protected. When exploring such methods, the engine then deduces behaviors regarding null-checking (among other things). Believing that dereferencing NULL shouldn't crash the system doesn't make it true. On many platforms, dereferencing a null pointer results inabnormal program termination, but this is not required by the standard. You're in a company-managed project. Original Java Specification Request (JSR) - Java Community Process Why are physically impossible and logically impossible concepts considered separate in terms of probability? Issues Components. 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. How to get rid of NullPointerException - freeCodeCamp.org As for today, the SE engine is able to explore non-overridable methods (static, for instance), when declared in the same file being analyzed. Since you cannot have a variable of type void, the pointer will not point to any data and therefore cannot be dereferenced. sonar-java. This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. Null pointer should not be dereferenced . For example the following program doesn't compile. NULL POINTERS SHOULD NOT BE DEREFERENCED - jobhuntley.com Im currently using SonarQube version 5.6.6. better way to handle this is to store the result of method invocation in a variable. Is there a single-word adjective for "having exceptionally strong moral principles"? , . Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). The final NCCE is actually more insidious than it seems at first. What is a NullPointerException, and how do I fix it? 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. How can we let this pass? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. A reference to Nothing should never be dereferenced/accessed. the Java one). 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). Making statements based on opinion; back them up with references or personal experience. 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. // <------- 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. Phew, we're agreed here. how to handle Sonarlint java:S2259 (Null pointers should not be