You're in a company-managed project. So no checking of the length is necessary (besides preventing integer overflow, which the compliant solution does). Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Issues Components. Is there a single-word adjective for "having exceptionally strong moral principles"? java There are many ways to resolve this. But passing 0 to memcpy() is not one of them. The user_data pointer could be invalid in other ways, such as pointing to freed memory. vegan) just to try it, does this inconvenience the caterers and staff? (I think you cover that in a different rule.) Ticket opened : Thanks a lot for the minimalized reproducer ! Good question! This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. 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. 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 . So Bar might not be initialized but then the last line of your example should not be evaluated in this case. 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. Software Engineering Institute
Im very new to sonar, is there a way to add methods to the whitelist? Null pointer should not be dereferenced . , NPE : 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" Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. Making statements based on opinion; back them up with references or personal experience. Not the answer you're looking for? Unfortunately, its actual state also has some limitations, like the one you are hitting here. In the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. assert(!invalid(p)); // or whatever, bool invalid(const void *p) { Possible fix: Assign a valid address to the pointer in all branches of the conditional statement.. Pointer can point to dynamically allocated memory. Why does the second compliant example permit using possibly-null pointers? We have a false positive with the " Null pointers should not be dereferenced -squid:S2259" rule : We have a "NullPointerException" false positive for which we do not know how to solve it. I added a comment to explain that SIZE_MAX is the limit of size_t. The standard will simply copy 0 byteswhich is essentially a no-op. Trying to understand how to get this basic Fourier Series. For example the following program doesn't compile. 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. [4] sonar-java. Made code more compliant with other rules. When B is null, The control reaches inside the main if block only when length of A is 1. "After the incident", I started to be more careful not to trip over things. To learn more, see our tips on writing great answers. 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. How to use Slater Type Orbitals as a basis functions in matrix method correctly? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. How to deal with "java.lang.OutOfMemoryError: Java heap space" error? So let me be more precise in my wording: I assert that a platform whose memcpy() did anything besides copy zero bytes when given n=0 and valid src and dest pointers was not C-standards-compliant. At worst, it could expose debugging information that would be useful to an attacker, or Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. . If copying takes place between objects that overlap, the behavior is undefined. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? Reports. 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 The purpose of a NULL pointer is not to cause a processor exception when it is dereferenced (although that is nice to have for debugging.) Much like dereferencing a dangling (or wild) pointer leads to undefined behavior, dereferencing a null pointer also leads to undefined behavior. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. which would allow us to systematically observe what you are having. rev2023.3.3.43278. 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. In Java, a special null value can be assigned to an object reference. > Further, if kstrdup() returns NULL, we should return ERR_PTR(-ENOMEM) to > the caller site. 4500 Fifth Avenue
The expected result here is solve the issue with sonarqube. If you preorder a special airline meal (e.g. 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. Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. 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]. In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. LANG.MEM.NPDLANG.STRUCT.NTADLANG.STRUCT.UPD, Null pointer dereferenceNull test after dereferenceUnchecked parameter dereference, Can detect violations of this rule. The issue arises when dereferenced pointers are used. A reference to null should never be dereferenced/accessed. I suppose we can check that that is not null, but we cannot check that it is valid (in any portable way). One could argue that all code examples would be redundant with the first pair. Please explain: Without this, we wont be able to help you. 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. I believe in this case, either expression would work. name result . Correct; a null pointer is not a valid pointer for the C library functions. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? sonarLint (3.2.) I'd guess null pointers are not valid, even though they point to 0 bytes. Off by one error: It is the third example. it could allow an attacker to bypass security measures. How do I align things in the following tabular environment? Hello. How handle the initialization of "responseDto" without "null" because is throwing the issue on sonar. PS: I also tried the code in android studio which uses Lint and got no warnings. 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 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(). That is why I explicitly check for this in my attempted solution. The problem is that something like %*pbl which reads a bitmask, will save the pointer to the bitmask in the buffer. 4. Are there tables of wastage rates for different fruit and veg? The only potential null is the return value of list(). util.regex.Matcher, java - Swing .getParent() . Dereferencing a null pointer is undefined behavior. 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! What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? But no where in that particular idiom would a NULL pointer necessarily be deferenced. That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. I reordered that code example to do all the checks before allocations. Connect and share knowledge within a single location that is structured and easy to search. You can compare a pointer with NULL to test for the special condition. The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. 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. A pointer to null (the 0 memory address) should never be dereferenced/accessed. SonarJava Version 5.9.2 (build 16552). All content is copyright protected. Share Improve this answer Follow answered Oct 5, 2017 at 16:27 SIZE_MAX is the largest possible value that a size_t could take, so it is not possible to have anything larger than SIZE_MAX. At best, such an exception will cause abrupt program termination. 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. Seems the analizer don't recognice the logic with the funcional object Optional. But when length of A is 1, the control never reaches the else block. I have checked on multiple . Solution 1, it looks like, today's solution tomorrow's problem. Why does Mister Mxyzptlk need to have a weakness in the comics? We resolved it by adding our tools path in the white list, and repackaging it. (C11, S7.24.2.1). 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. 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. 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. A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). Recovering from a blunder I made while emailing a professor. In the meantime, Im locking this thread. Making statements based on opinion; back them up with references or personal experience. It is generally accepted that zeroing a pointer is a good way to mark it as invalid and dereferencing an invalid pointer is a bug. How can this new ban on drag possibly be considered constitutional? And the semantics, as I said, are different. Thanks for contributing an answer to Stack Overflow! In C# and Java, all reference types can point to null. sonarlint, sonarLint (3.2.) attacker to bypass security measures. Which version of SonarJava plugin do you have? 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). It could be non-null the first time but not the second time, sonar does not know this. Also, the term 'pointer' is bad (but maybe it comes from the FindBugs tool): Java doesn't have pointers, it has references. validated for null in your method declaration with it: 2008-2023 SonarSource S.A., Switzerland. Using Kolmogorov complexity to measure difficulty of problems? 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. In my experience, there are reasons to check for a NULL pointer other than dereferencing it. ssize_t (*aio_read)(struct kiocb *, char __user *, size_t . https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx 2008-2023 SonarSource S.A., Switzerland. Essentially, this code and the previous dereference disagree as to whether this value is allowed to be null. The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. 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). Doing so will at best cause abrupt program termination, without the Is there a single-word adjective for "having exceptionally strong moral principles"? This will normally lead to an unhandled error, resulting in a segmentation fault. Status: Dormant. Find centralized, trusted content and collaborate around the technologies you use most. 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. 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. Is it suspicious or odd to stand by the gate of a GA airport watching the planes? Obviously the value of that pointer could have changed since the . All rights are expressly reserved. 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. It is still a pointer though, to use it you just have to cast it to another kind of pointer first. This is indeed an obvious False Positive from the rule. There are many ways to resolve this. The same problem we will have with "Add at least one assertion to this test case." Does Counterspell prevent from any further spells being cast on a given turn? A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. A value is checked here to see whether it is null, but this value can't be null because it was previously dereferenced and if it were null a null pointer exception would have occurred at the earlier dereference. The SonarJava SE engine is however, by default, not configured to explore methods declared in other files (in your case, your utility class CheckUtils). What is pointed to should only be deleted if it was created with new. Is null check needed before calling instanceof? To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. That is, sets equivalent to a proper subset via an all-structure-preserving bijection. Now, you can find the list of whitelisted methods here. in above code, These can be: Invoking a method from a null object. C# static code analysis: Null pointers should not be dereferenced Products In-IDE IDE extension that lets you fix coding issues before they exist! 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. Is there a proper earth ground point in this switch box? Null pointer should not be dereferenced , 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 The solution that I recommend is not work with null returns or variables on Java, try to avoid it. You need to benchmark. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. Im currently using SonarQube version 5.6.6. better way to handle this is to store the result of method invocation in a variable. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. In C, dereferencing a null pointer is undefined behavior. I don't need to do this validation again. that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. Minimising the environmental effects of my dyson brain. @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. You're in a company-managed project. "After the incident", I started to be more careful not to trip over things. Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". But when length of A is 1, the control never reaches the else block. Optimizers are optimizing based on this latitude and have been for years. I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. I feel my situation is not as complicated. Asking for help, clarification, or responding to other answers. With their flexibility, void pointers also bring some constraints. Thus we should check > this kstrdup() operation. 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. Whats the grammar of "For those whose stories they are"? Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to bypass security measures. Alternate Terms Relationships Do "superinfinite" sets exist? - the incident has nothing to do with me; can I use this this way? Hi @Michael! Key here (explains table format and definitions), EXP34-C = Union( CWE-690, list) where list =. Your assertion is not backed by the wording in the standard, nor by common implementer understanding. This compliant solution eliminates the null pointer deference by initializing sk to tun->sk following the null pointer check. 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. We can see that at obj.run(), obj can not be null, but is pointed out by Sonar. My question is; is my solution incorrect? Find centralized, trusted content and collaborate around the technologies you use most. This sounds indeed like a bug in the flow when an exception is raised. very old code or C code being worked into c++ may have functions that expect the user to delete the data. 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. This code also violates ERR33-C. Detect and handle standard library errors. Accessing or modifying a null object's field. (from res.getBody().getServiceResult() ). Did any DOS compatibility layers exist for any UNIX-like systems before DOS started to become outmoded? So we have to check all the arguments before performing any actions. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? Extended Description NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions. At this point we define size as strlen(input_str) + 1. How do you ensure that a red herring doesn't violate Chekhov's gun? Java Specification Participation Agreement version in use: 2.0. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. (In contrast, the case of passing 0 bytes to malloc is addressed in C11.)