null pointers should not be dereferenced

This compliant solution eliminates the null pointer deference by initializing sk to tun->sk following the null pointer check. When B is null, The control reaches inside the main if block only when length of A is 1. Im currently using SonarQube version 5.6.6. better way to handle this is to store the result of method invocation in a variable. How to deal with "java.lang.OutOfMemoryError: Java heap space" error? The final NCCE is actually more insidious than it seems at first. 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. All content is copyright protected. Such long getter chains can also be replaced with Optional + map + ifPresent lambda style. 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). I would also guess that pointers that point to the one-past-the-end of an array are also invalid. 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). Why do academics stay as adjuncts for years rather than move around? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. This engine is validating execution paths and checking for non-null values or null-check along the way, exploring all the possibilities. Doing so will cause a NullReferenceException to be thrown. 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. 2008-2023 SonarSource S.A., Switzerland. Asking for help, clarification, or responding to other answers. , NPE : null-, . When I added the not null validation as sonar suggest. A reference to Nothing should never be dereferenced/accessed. 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. In my experience, there are reasons to check for a NULL pointer other than dereferencing it. () 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. Powered by Discourse, best viewed with JavaScript enabled. 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. sonarLint (3.2.) ncdu: What's going on with this second size column? How can this new ban on drag possibly be considered constitutional? And if there is no pointer_default declaration, then the default default is ref. Thanks for your relpy. But even with this, the concerned object it tagged as a possible NullPointerException problem. sonarlint complains that An awesome tip to avoid NPE is to return empty strings or empty collections rather than null. And the semantics, as I said, are different. A reference to null should never be dereferenced/accessed. Calls to extension methods are not reported because they can still operate on null values. For the time being, I would unfortunately recommend to mark as False Positive the issue. I don't need to do this validation again. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. 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. raiseException() return, Sonar It looks like a logic bug, which can cause a memory leaking. Ticket opened : Thanks a lot for the minimalized reproducer ! Trying to understand how to get this basic Fourier Series. How do you ensure that a red herring doesn't violate Chekhov's gun? What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? 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. 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 the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. Minimising the environmental effects of my dyson brain. uninitialized reference-type class members. Finally my method is returning a response with value of restTemplate. The problem is, I hope this code's result to be <5,3> and <9,6> BUT the console only shows me <5,3> and <9,3>. Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. The expected result here is solve the issue with sonarqube. Is there a single-word adjective for "having exceptionally strong moral principles"? Correct; a null pointer is not a valid pointer for the C library functions. [4] What are the effects of exceptions on performance in Java? Doing so will at best cause abrupt program termination, without the Find centralized, trusted content and collaborate around the technologies you use most. 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. SonarJava Version 5.9.2 (build 16552). Fixed by #1156 Contributor 94cb5f8 boris-unckel on Jul 28, 2021 9e62550 boris-unckel mentioned this issue on Jul 28, 2021 Closes #1155 - Null pointers should not be dereferenced #1156 Merged best, such an exception will cause abrupt 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]. Things go fine now. Sonar is ok. Depending on whether the pointer is valid (i.e. Can I tell police to wait and call a lawyer when served with a search warrant? Here is our source code: Sign in to download full-size image Trying to understand how to get this basic Fourier Series. Thus we should check > this kstrdup() operation. 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. Just a few words about the rule now. Connect and share knowledge within a single location that is structured and easy to search. SonarQube - Null Pointer Dereference Issue java simonsirak (Simon Sirak) June 14, 2018, 1:18pm 1 Hi! 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. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. Thank you for clarifying your assertion until I understood it properly. ), 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). 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. It's still illegal. What does "Could not find or load main class" mean? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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 The solution that I recommend is not work with null returns or variables on Java, try to avoid it. Doing so will cause a NullReferenceException to be thrown. Dereferencing a null pointer is undefined behavior, typically abnormal program termination. The method isNR(minRating) is a helper method that validate among other things, if the object minRating is null. When a variable is declared as being a pointer to type void, it is known as a generic pointer. . At best, such an exception will cause abrupt program termination. That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. sometimes FP occurs. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Powered by Discourse, best viewed with JavaScript enabled. Check whether a String is not Null and not Empty. 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 solution also ensures that theuser_data pointer is not null. How can we prove that the supernatural or paranormal doesn't exist? You can use Optional instead. 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} static-code-analysis Does it just mean failing to correctly check if a value is null? 4. 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. All rights are expressly reserved. EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. Rule squid:S2259 is based on a Symbolic Execution (SE) engine. There are many ways to resolve this. In the meantime, Im locking this thread. However there is no portable way to verify that the pointer is valid, other than checking for null. https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java. I added an assertion to that compliant code example. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? We. 11 Sep, 2006. In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. Is it possible to rotate a window 90 degrees if it has the same length and width? sonar-java. As for copy vs pointer/reference - it depends. Trying to understand how to get this basic Fourier Series. 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. 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. validated for null in your method declaration with it: 2008-2023 SonarSource S.A., Switzerland. In the simplest case, this function just returns the result of calling kmalloc. SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. A pointer to null (the 0 memory address) should never be dereferenced/accessed. Thanks for contributing an answer to Stack Overflow! When you have a variable of non-primitive type, it is a reference to an object. I have checked on multiple . Search for vulnerabilities resulting from the violation of this rule on the CERT website. 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. If you preorder a special airline meal (e.g. util.regex.Matcher, java - Swing .getParent() . You can compare a pointer with NULL to test for the special condition. In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. Haiku is a free and open-source operating system for PC designed to be binary compatible with the BeOS operating system and embodying the basic ideas of BeOS. 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 C# and Java, all reference types can point to null. Connect and share knowledge within a single location that is structured and easy to search. Do not dereference null pointers Created by Jeffrey Gennari, last modified by Jill Britton on Jan 18, 2023 Dereferencing a null pointer is undefined behavior. Avoid Returning null from Methods. Thanks for the feedback. Goal which version of SonarQube are you using? But when length of A is 1, the control never reaches the else block. A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. The standard will simply copy 0 byteswhich is essentially a no-op. At best, such an exception will cause abrupt program termination. Can I tell police to wait and call a lawyer when served with a search warrant? Why is there a voltage on my HDMI and coaxial cables? Is there a proper earth ground point in this switch box? My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? False-positives are pointed out in other SO posts (1 & 2), where nulls are involved across functions and procedures. attacker to bypass security measures. To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. Seems the analizer don't recognice the logic with the funcional object Optional. What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. 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" ), 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. IMHO, the rule title should be changed to something less general. That is why I explicitly check for this in my attempted solution. Hello. Sonar is ok. Sonar can't determine that the helper method did the null validation. Which @NotNull Java annotation should I use? LANG.MEM.NPDLANG.STRUCT.NTADLANG.STRUCT.UPD, Null pointer dereferenceNull test after dereferenceUnchecked parameter dereference, Can detect violations of this rule. Unfortunately, its actual state also has some limitations, like the one you are hitting here. (C11, S7.24.2.1). CWE-476: NULL Pointer Dereference: 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. 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. Two null pointers will always be equal to each other. With their flexibility, void pointers also bring some constraints. The user_data pointer could be invalid in other ways, such as pointing to freed memory. By explicitly teaching the C++ standard class behaviors we can make the Analyzer to find more bugs related to modern C++ code. Is there a single-word adjective for "having exceptionally strong moral principles"? )}"); Styling contours by colour and by line thickness in QGIS. 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. I say "theoretical" because I have not successfully produced strings of this length in testing. One could argue that all code examples would be redundant with the first pair. Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. Is there a proper earth ground point in this switch box? Batch split images vertically in half, sequentially numbering the output files, Recovering from a blunder I made while emailing a professor. When I scan with sonar-lint in idea, it seams white list is useful, but when use sonar-scanner, always FP, org.springframework.util.CollectionUtils#isEmpty Solution 1, it looks like, today's solution tomorrow's problem. . That is, sets equivalent to a proper subset via an all-structure-preserving bijection. This code also violates ERR33-C. Detect and handle standard library errors. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Instead use String.valueOf (object). Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? @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. Asking for help, clarification, or responding to other answers. 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 . 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. Since you cannot have a variable of type void, the pointer will not point to any data and therefore cannot be dereferenced. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. context.RaiseException , (/) Passing ownership of something also requires pointers. Carnegie Mellon University Automated Detection Null pointer dereferences can happen in path-dependent ways. 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. rev2023.3.3.43278. Additionally, if input_str is a null pointer, the call to strlen() dereferences a null pointer, also resulting in undefined behavior. Software project. Which ensures that the chunkdata pointer is valid, but makes no such check to the user_data pointer. Dereferencing a null pointer can lead to a denial of service. How can we let this pass? New replies are no longer allowed. How do I align things in the following tabular environment? So Bar might not be initialized but then the last line of your example should not be evaluated in this case. Extended Description NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions. 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. Null pointer should not be dereferenced . IDE extension that lets you fix coding issues before they exist! The null concept refers to the idea that a pointer can hold a special value that is not equal to another pointer. Making statements based on opinion; back them up with references or personal experience. JCP version in use: 2.6. 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. Software Engineering Institute The same problem we will have with "Add at least one assertion to this test case." The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. I believe that dereferencing NULL should not crash the system, should not allow a write to a NULL pointer area, but should always set errno, If I am a hacker, could I trap a null failure that would force a memory dump. Using platform-specific means (e.g. Im having trouble understanding your problem. If the project is not compiled, and without sonar.java.binaries whether the white list takes effect? We cannot understand how there could be a null pointer exception at the reported line. To learn more, see our tips on writing great answers. Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? 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. 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. Using Kolmogorov complexity to measure difficulty of problems? Hi @Michael! io.NotSerializableException : java. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . The idea is not to guarantee validity, but to catch a substantial number of problems that could occur. ncdu: What's going on with this second size column? - the incident has nothing to do with me; can I use this this way? 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. You're in a company-managed project. Trying to understand how to get this basic Fourier Series. If you write [ref], then a null pointer is not allowed, but if you write [unique], then a null pointer is permitted. 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. }. Is null check needed before calling instanceof? How handle the initialization of "responseDto" without "null" because is throwing the issue on sonar. The result of calling such a helper function should be . Does a summoned creature play immediately after being summoned by a ready action? Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. The only potential null is the return value of list(). Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. All content is copyright protected. 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. java Description: This JSR will work to develop standard annotations (such as @NonNull) that can be applied to Java programs to assist tools that detect software defects. Reports. But when length of A is 1, the control never reaches the else block. So we have to check all the arguments before performing any actions. Connect and share knowledge within a single location that is structured and easy to search. Good question! Currently I'm working with SonarQube solving issues but I'm facing a trouble to how handle null pointers that shouldn't be dereferenced. Do "superinfinite" sets exist? Connect and share knowledge within a single location that is structured and easy to search. It also uses the unsigned type size_t to pass the length parameter, ensuring that negative values are not passed to func(). https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx 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?) Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. Perhaps this could be done with a special constraint that will notify the SE engine that we learned from a Debug.Assert call. Pittsburgh, PA 15213-2612 However, memory allocation > functions such as kstrdup() may fail and returns NULL. This is a matter of style, and also following code walkthrough. 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]. So the SIZE_MAX check was unnecessary. 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. 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 (?,?,?,?,?,?,?,? Null pointers should not be dereferenced. 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. How do you ensure that a red herring doesn't violate Chekhov's gun? - the incident has nothing to do with me; can I use this this way? The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). How to use Slater Type Orbitals as a basis functions in matrix method correctly? What is a NullPointerException, and how do I fix it?,What are Null Pointer Exceptions (java.lang.NullPointerException) and what causes them? Write a semantic patch to nd cases where the result of calling kmalloc is dereferenced with no previous NULL pointer test. What is null pointer exception in android. 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. On many platforms, dereferencing a null pointer results inabnormal program termination, but this is not required by the standard. isEmpty(Collection collection) I'd guess WG14 has considered these questions, but I haven't until now :). Null pointer should not be dereferenced , If you call connect() function, it better do the connection, but failing simply because some ptr is NULL is not good behaviour -- failures should . res.getBody() == null || res.getBody().getServiceResult() == null). Made code more compliant with other rules. 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! To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. 1 Answer Sorted by: 1 Your code is ok. Then we hit memcpy with length 0. rev2023.3.3.43278. 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. NullPointerException is a RuntimeException. 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. Is a PhD visitor considered as a visiting scholar? The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. 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?) Dereferencing > this null pointer may cause the kernel go wrong.

What Disease Did, Bokuto Have In Another Life, Articles N