null pointers should not be dereferenced

IDE extension that lets you fix coding issues before they exist! But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. How can this new ban on drag possibly be considered constitutional? The user_data pointer could be invalid in other ways, such as pointing to freed memory. 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. At worst, it could expose debugging information that would be useful to an attacker, or PS: I also tried the code in android studio which uses Lint and got no warnings. Small typo nit: "such as if i t pointed to freed memory" meant to say "if it" instead (removing whitespace). I suppose we can check that that is not null, but we cannot check that it is valid (in any portable way). Why is there a voltage on my HDMI and coaxial cables? This sounds indeed like a bug in the flow when an exception is raised. At worst, it could expose debugging information that would be useful to an attacker or it could allow an 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. Search for vulnerabilities resulting from the violation of this rule on the CERT website. Obviously the value of that pointer could have changed since the . Clearly the standard enumerates 1 case of undefined behavior, but makes no special mention of n=0. 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. Appropriate typecasting is necessary. The above check can't hurt, as I guess you could have a system with a 32-bit size_t that had a ton of memory and had some crazy banking/selector scheme with pointers. 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. SonarLint IntelliJ 4.0.0.2916 Java Rule 'Null pointers should not be dereferenced' I'm getting this fault in the next code when obj can't be null in any scenario. Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, S2259: Null pointers should not be dereferenced, find the list of whitelisted methods here, Rule java:S2259: False-positive NullPointerException bug logged when variable is null-checked by an imported method, What is the issue you are observing, in details, What version of SonarSource products you are using, as well as the version of SonarJava. {"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. I reordered that code example to do all the checks before allocations. My question is; is my solution incorrect? sometimes FP occurs. 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. 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 So the SIZE_MAX check was unnecessary. Reports. We might set a pointer to null even if we are not freeing a object, simply to dissociate one object from another: tty_driver->tty = NULL; /* detach low level driver from the tty device */ Why are physically impossible and logically impossible concepts considered separate in terms of probability? A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. Doing so will cause a NullPointerException to be thrown. 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. A NULL pointer can be dereferenced when signatures are being verified on PKCS7 signed or signedAndEnveloped data. 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. But even with this, the concerned object it tagged as a possible NullPointerException problem. Dereferencing a null pointer is undefined behavior. 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. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. What is pointed to should only be deleted if it was created with new. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} rev2023.3.3.43278. Does Counterspell prevent from any further spells being cast on a given turn? How to use Slater Type Orbitals as a basis functions in matrix method correctly? 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). 1 Answer Sorted by: 1 Your code is ok. Is there a single-word adjective for "having exceptionally strong moral principles"? The expected result here is solve the issue with sonarqube. 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. ability to run any cleanup processes. When B is null, The control reaches inside the main if block only when length of A is 1. Is there a single-word adjective for "having exceptionally strong moral principles"? And fwstr > is dereferenced in the following codes. 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. 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]. There are many ways to resolve this. In layman's terms, a null pointer is a pointer to an address in the memory space that does not have a meaningful value and cannot be referenced by the calling program, for whatever reason. Find centralized, trusted content and collaborate around the technologies you use most. SonarJava Version 5.9.2 (build 16552). So the first execution of ValidateNumber inside the foreach works fine and valid is set to true.The second execution throws the exception and exception is set in the catch-Block.. Not the answer you're looking for? it could allow an attacker to bypass security measures. Recovering from a blunder I made while emailing a professor. io.NotSerializableException : java. 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. IDE extension that lets you fix coding issues before they exist! Thanks for your relpy. This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. The issue arises when dereferenced pointers are used. String *x, y; X is a pointer to a string, Y is a string & = address of variable/ operator || referencing operator * = value of address || dereferencing operator Pointers = stores memory address as its variables NULL pointer = a constant with a value of zero defined || assigned to null Void pointer = a pointer that is not associated with any data types New operator = denotes a request for . 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. Im having trouble understanding your problem. Since you cannot have a variable of type void, the pointer will not point to any data and therefore cannot be dereferenced. I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. 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! Some Interesting Facts: 1) void pointers cannot be dereferenced. It could be non-null the first time but not the second time, sonar does not know this. Seems the analizer don't recognice the logic with the funcional object Optional. Isn't easier just to check valid range of length? If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. Your code needs to do something about the possible NullPointerException when some exception is caught, because in this scenario the responseDto will be null. What is a serialVersionUID and why should I use it? Minimising the environmental effects of my dyson brain. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. sonarqube Batch split images vertically in half, sequentially numbering the output files, Recovering from a blunder I made while emailing a professor. This sounds indeed like a bug in the flow when an exception is raised. 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 At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to bypass security measures. can have the value zero on a call to that function. S2259: Null pointers should not be dereferenced java tsubasa (Jiaoyang Ma) January 11, 2019, 6:57am 1 versions used (SonarQube, Scanner, language analyzer) SonarQube Version 6.7.2 (build 37468) SonarJava Version 5.9.2 (build 16552) minimal code sample to reproduce (with analysis parameter, and potential instructions to compile). "After the incident", I started to be more careful not to trip over things. Trying to understand how to get this basic Fourier Series. 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.) JCP version in use: 2.6. Currently I'm working with SonarQube solving issues but I'm facing a trouble to how handle null pointers that shouldn't be dereferenced. (from res.getBody().getServiceResult() ). I added an assertion to that compliant code example. Such long getter chains can also be replaced with Optional + map + ifPresent lambda style. Shouldn't the function check all pointers before dereferencing them or passing them to another function? Calls to extension methods are not reported because they can still operate on null values. . raiseException() return, Sonar This code also violates ERR33-C. Detect and handle standard library errors. 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. Recovering from a blunder I made while emailing a professor. 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. However, memory allocation > functions such as kstrdup() may fail and returns NULL. Which version of SonarJava plugin do you have? NullPointerException is a RuntimeException. ssize_t (*aio_read)(struct kiocb *, char __user *, size_t . It also adds assertions to document that certain other pointers must not be null. 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. The fact that you can't pass a null (no object) with a reference parameter can be a reason to use a pointer instead. , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow Hi Andreas, Thanks for the feedback. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. When you have a variable of non-primitive type, it is a reference to an object. 11 Sep, 2006. Not the answer you're looking for? So we have to check all the arguments before performing any actions. Alternate Terms Relationships We cannot understand how there could be a null pointer exception at the reported line. static-code-analysis Just because something is a pointer does not mean you should call delete . If you preorder a special airline meal (e.g. NULL vs Uninitialized pointer - An uninitialized pointer stores an undefined value. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, SonarQube null pointers should not be dereferenced on try/catch, How Intuit democratizes AI development across teams through reusability. If copying takes place between objects that overlap, the behavior is undefined. Making statements based on opinion; back them up with references or personal experience. context.RaiseException . Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". isEmpty(Map map) Making statements based on opinion; back them up with references or personal experience. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. rev2023.3.3.43278. All content is copyright protected. Which @NotNull Java annotation should I use? Not the answer you're looking for? https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx I feel my situation is not as complicated. 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). What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. We. Thanks for contributing an answer to Stack Overflow! But no where in that particular idiom would a NULL pointer necessarily be deferenced. Using Kolmogorov complexity to measure difficulty of problems? How to tell which packages are held back due to phased updates. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. There are many ways to resolve this. 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). Null pointer should not be dereferenced , Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? And the semantics, as I said, are different. 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. NullPointerException is thrown when program attempts to use an object reference that has the null value. sonar-java. At this point we define size as strlen(input_str) + 1. I'd guess null pointers are not valid, even though they point to 0 bytes. That makes sense. What is the point of Thrower's Bandolier? Powered by Discourse, best viewed with JavaScript enabled. Is there a single-word adjective for "having exceptionally strong moral principles"? Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method.

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null pointers should not be dereferenced