null pointers should not be dereferenced

Is there a proper earth ground point in this switch box? Avoid Returning null from Methods. What does it mean that a reference must refer to an object, not a dereferenced null pointer? it could allow an attacker to bypass security measures. You can compare a pointer with NULL to test for the special condition. attacker to bypass security measures. Asking for help, clarification, or responding to other answers. IDE extension that lets you fix coding issues before they exist! What is the point of Thrower's Bandolier? In C/C++ speak, 'dereferencing' simply means getting the object that a pointer . It is useful to have a function with portable interface but platform-dependent implementation: extern bool invalid(const void *); Java Specification Participation Agreement version in use: 2.0. If you preorder a special airline meal (e.g. {"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. There is no guarantee that subsequent invocations are returning the same value, thats why issue is raised. Just a few words about the rule now. In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. I have checked on multiple . Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. Using platform-specific means (e.g. uninitialized reference-type class members. 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. To learn more, see our tips on writing great answers. Also, the term 'pointer' is bad (but maybe it comes from the FindBugs tool): Java doesn't have pointers, it has references. The problem is that something like %*pbl which reads a bitmask, will save the pointer to the bitmask in the buffer. 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. The user_data pointer could be invalid in other ways, such as pointing to freed memory. return p == NULL || (char *)p < &_etext; Put a new ResponseEntity is wrong because I won't know what will be the answer for the status of http. That makes sense. How do you ensure that a red herring doesn't violate Chekhov's gun? Check whether a String is not Null and not Empty. 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. sometimes FP occurs. Why are physically impossible and logically impossible concepts considered separate in terms of probability? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Is there a solution to add special characters from software and how to do it, Acidity of alcohols and basicity of amines. static-code-analysis But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. In the code, we check the not nullity with java.util.Objects.nonNull(). In the simplest case, this function just returns the result of calling kmalloc. Ticket opened : Thanks a lot for the minimalized reproducer ! 412-268-5800, 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 pointer. Much like dereferencing a dangling (or wild) pointer leads to undefined behavior, dereferencing a null pointer also leads to undefined behavior. Goal Trying to understand how to get this basic Fourier Series. Doing so will at best cause abrupt program termination, without the MSBuild SonarQube Runner Resharper Plugin receives skipping info errors File not in sonarqube, SonarQube jenkins plugin returns "Server returned HTTP response code: -1, message: 'null' for URL: https://api.github.com/user", SonarQube: Ignore issues in blocks not working with regex, sonarLint complains "Null pointers should not be dereferenced (squid:S2259)" despite that possibility being handled, Java: (false?) A NULL pointer can be dereferenced when signatures are being verified on PKCS7 signed or signedAndEnveloped data. Two null pointers will always be equal to each other. Shouldn't the function check all pointers before dereferencing them or passing them to another function? 3.7. It could be non-null the first time but not the second time, sonar does not know this. All content is copyright protected. (In contrast, the case of passing 0 bytes to malloc is addressed in C11.) This engine is validating execution paths and checking for non-null values or null-check along the way, exploring all the possibilities. Pittsburgh, PA 15213-2612 The 2nd NCCE/CS pair seems redundant with the first NCCE/CS pair. Connect and share knowledge within a single location that is structured and easy to search. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. which would allow us to systematically observe what you are having. Im currently using SonarQube version 5.6.6. better way to handle this is to store the result of method invocation in a variable. 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. How do I align things in the following tabular environment? isEmpty(Collection collection) You're in a company-managed project. Null pointer should not be dereferenced , Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. This issues is displayed by SonarQube. Doing so will cause a NullReferenceException to be thrown. The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. Small typo nit: "such as if i t pointed to freed memory" meant to say "if it" instead (removing whitespace). This code also violates ERR33-C. Detect and handle standard library errors. I don't need to do this validation again. At worst, it could expose debugging information that would be useful to an attacker or it could allow an Why do academics stay as adjuncts for years rather than move around? 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). 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. 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. It looks like a logic bug, which can cause a memory leaking. This sounds indeed like a bug in the flow when an exception is raised. 2008-2023 SonarSource S.A., Switzerland. Thanks for your relpy. Software project. 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. Not the answer you're looking for? The final NCCE is actually more insidious than it seems at first. We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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 Dereferencing a null pointer is undefined behavior. The fact that you can't pass a null (no object) with a reference parameter can be a reason to use a pointer instead. Is a PhD visitor considered as a visiting scholar? Reports. Using Kolmogorov complexity to measure difficulty of problems? The alert is related to the sonar rule : Null pointers should not be dereferenced. Find centralized, trusted content and collaborate around the technologies you use most. The issue arises when dereferenced pointers are used. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? The return value from strchr() is often NULL, but the dev might know that a specific strchr() function call will not return NULL. @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. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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. How do I align things in the following tabular environment? vegan) just to try it, does this inconvenience the caterers and staff? It's a modular system with the . How to use Slater Type Orbitals as a basis functions in matrix method correctly? When exploring such methods, the engine then deduces behaviors regarding null-checking (among other things). This is indeed an obvious False Positive from the rule. You're in a company-managed project. 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. Thanks for contributing an answer to Stack Overflow! If you try to access any member variables or methods with that variable, you are trying to dereference it. How to tell which packages are held back due to phased updates. Instead use String.valueOf (object). 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). To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. 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. I've changed it to say null pointer instead of invalid pointer. Find centralized, trusted content and collaborate around the technologies you use most. () Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. Thanks for contributing an answer to Stack Overflow! 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. The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. When you have a variable of non-primitive type, it is a reference to an object. All rights are expressly reserved. Find centralized, trusted content and collaborate around the technologies you use most. (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). Is the God of a monotheism necessarily omnipotent? 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 can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? Additionally, if input_str is a null pointer, the call to strlen() dereferences a null pointer, also resulting in undefined behavior. So the SIZE_MAX check was unnecessary. Unlike reference types, pointer types are not tracked by the default garbage . Making statements based on opinion; back them up with references or personal experience. You can use Optional instead. 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. However there is no portable way to verify that the pointer is valid, other than checking for null. 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. 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]. 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. Is it possible to create a concave light? http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. Is null check needed before calling instanceof? void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. A reference to Nothing should never be dereferenced/accessed. Possible fix: Assign a valid address to the pointer in all branches of the conditional statement.. Pointer can point to dynamically allocated memory. Using Kolmogorov complexity to measure difficulty of problems? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, It is a false positive, but it might be a good idea not to do the, Sonar false-positive on rule: Null pointers should not be dereferenced, How Intuit democratizes AI development across teams through reusability. IDE extension that lets you fix coding issues before they exist! False-positives are pointed out in other SO posts (1 & 2), where nulls are involved across functions and procedures. 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. Connect and share knowledge within a single location that is structured and easy to search. context.RaiseException , (/) Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. And the semantics, as I said, are different. the Java one). What is generic pointer? I think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. 3.Null pointers should not be derefer enced/accessed. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Note that it doesn't know how to check for non-heap, non-stack. Issues Components. To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. Making statements based on opinion; back them up with references or personal experience. Believing that dereferencing NULL shouldn't crash the system doesn't make it true. Can I tell police to wait and call a lawyer when served with a search warrant? 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. Accessing or modifying a null object's field. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. When and how should I use a ThreadLocal variable? Ah, gotcha. Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. 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. At best, such an exception will cause abrupt program termination. Issues Components. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. Making statements based on opinion; back them up with references or personal experience. Is it possible to rotate a window 90 degrees if it has the same length and width? If copying takes place between objects that overlap, the behavior is undefined. Asking for help, clarification, or responding to other answers. rev2023.3.3.43278. Rule squid:S2259 is based on a Symbolic Execution (SE) engine. 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. 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} SonarJava Version 5.9.2 (build 16552). Can I tell police to wait and call a lawyer when served with a search warrant? Appropriate typecasting is necessary. But when length of A is 1, the control never reaches the else block. 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. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? 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. Connect and share knowledge within a single location that is structured and easy to search. What are the effects of exceptions on performance in Java? Styling contours by colour and by line thickness in QGIS. ), 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. Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). We cannot understand how there could be a null pointer exception at the reported line. Aaron:I suspect we are talking past each other. Does Counterspell prevent from any further spells being cast on a given turn? Do "superinfinite" sets exist? Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. Good question! The null pointer check for writing or dereferencing should be a compiler flag or library setting. Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, SonarQube - Null Pointer Dereference Issue. sonarlint complains that SonarQube - Null Pointer Dereference Issue java simonsirak (Simon Sirak) June 14, 2018, 1:18pm 1 Hi! Mutually exclusive execution using std::atomic? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx . To learn more, see our tips on writing great answers. 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. Why does the second compliant example permit using possibly-null pointers? It is still a pointer though, to use it you just have to cast it to another kind of pointer first. Depending on whether the pointer is valid (i.e. This compliant solution eliminates the null pointer deference by initializing sk to tun->sk following the null pointer check. Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. Optimizers are optimizing based on this latitude and have been for years. 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. The same problem we will have with "Add at least one assertion to this test case." PS: I also tried the code in android studio which uses Lint and got no warnings. // <------- 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. How can we let this pass? You need to benchmark. If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? Asking for help, clarification, or responding to other answers. 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. 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. But even with this, the concerned object it tagged as a possible NullPointerException problem. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? 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" , NPE : null-, . An awesome tip to avoid NPE is to return empty strings or empty collections rather than null. Please explain: Without this, we wont be able to help you. Do not use a null in a case where an object is required, https://gcc.gnu.org/gcc-4.9/porting_to.html, Prior to 2018-01-12: CERT: Unspecified Relationship, Pointer Casting and Pointer Type Changes [HFC], Dereferencing an out-of-domain pointer [nullref], Section 5.2.18, "Null-Pointer Dereference", Dereferencing null pointers that were not returned by a function. Software Engineering Institute By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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. Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. Interactions/interfaces with C can't use references. PS: I also tried the code in android studio which uses Lint and got no warnings. A nonnegative return value represents the number of bytes successfully read (the return value is a "signed size" type, usually the native integer type for the target platform). Doing so will cause a NullReferenceException to be thrown. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? 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! By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? We can see that at obj.run(), obj can not be null, but is pointed out by Sonar. extern char _etext; At worst, it could expose debugging information that would be useful to an attacker, or JCP version in use: 2.6. Many platforms can support testing for those also. Carnegie Mellon University int changed to size_t and if size_t parameter's is zero, allocate one word. Extended Description NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions. 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. Is the God of a monotheism necessarily omnipotent? I suggest that this topic needs to include calloc() and realloc() Refer to Linux man pages online for more enlightenment about malloc(), and friends. Write a semantic patch to nd cases where the result of calling kmalloc is dereferenced with no previous NULL pointer test. Solution 1, it looks like, today's solution tomorrow's problem.

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