I've changed it to say null pointer instead of invalid pointer. As for today, the SE engine is able to explore non-overridable methods (static, for instance), when declared in the same file being analyzed. can have the value zero on a call to that function. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. We really appreciate your help. 4500 Fifth Avenue
The result of calling such a helper function should be . 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. Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. 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. Also, the term 'pointer' is bad (but maybe it comes from the FindBugs tool): Java doesn't have pointers, it has references. The correct idiom is to only allocate storage if the pointer is currently NULL. java Isn't easier just to check valid range of length? In the simplest case, this function just returns the result of calling kmalloc. Recovering from a blunder I made while emailing a professor. Thanks for contributing an answer to Stack Overflow! The idea is not to guarantee validity, but to catch a substantial number of problems that could occur. Note that it doesn't know how to check for non-heap, non-stack. raiseException() return, Sonar 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 Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? When B is null, The control reaches inside the main if block only when length of A is 1. If you say [in] or [out] without a modifier, then the modifier defaults to the pointer_default for the enclosing class. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? validated for null in your method declaration with it: 2008-2023 SonarSource S.A., Switzerland. You can compare a pointer with NULL to test for the special condition. It could be non-null the first time but not the second time, sonar does not know this. rev2023.3.3.43278. which version of SonarQube are you using? Status: Dormant. It could be non-null the first time but not the second time, sonar does not know this. Trying to understand how to get this basic Fourier Series. This issues is displayed by SonarQube. These can be: Invoking a method from a null object. Not the answer you're looking for? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. 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. Believing that dereferencing NULL shouldn't crash the system doesn't make it true. What is a serialVersionUID and why should I use it? 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! Good question! 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. So no checking of the length is necessary (besides preventing integer overflow, which the compliant solution does). Just a few words about the rule now. Hi Andreas, Thanks for the feedback. When I added the not null validation as sonar suggest. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? Made code more compliant with other rules. Avoid Returning null from Methods. . Is a PhD visitor considered as a visiting scholar? Doing so will cause a NullReferenceException to be thrown. Thanks for contributing an answer to Stack Overflow! SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. sonarlint complains that Ticket opened : Thanks a lot for the minimalized reproducer ! 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. Batch split images vertically in half, sequentially numbering the output files, Recovering from a blunder I made while emailing a professor. In C, dereferencing a null pointer is undefined behavior. Using platform-specific means (e.g. What methods/tools can be used to determine the cause so that you stop the exception from causing the progra. If you write [ref], then a null pointer is not allowed, but if you write [unique], then a null pointer is permitted. 3.7. Calls to extension methods are not reported because they can still operate on null values. sonarqube Its purpose is to serve as a special value for a pointer that could indicate a special condition in your program. Basically, yes. At worst, it could expose debugging information that would be useful to an attacker or it could allow an 4. What are the effects of exceptions on performance in Java? // <------- 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. Which version of SonarJava plugin do you have? void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). (In contrast, the case of passing 0 bytes to malloc is addressed in C11.) 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. return p == NULL || (char *)p < &_etext; Automated Detection Null pointer dereferences can happen in path-dependent ways. Can I tell police to wait and call a lawyer when served with a search warrant? When exploring such methods, the engine then deduces behaviors regarding null-checking (among other things). Setup is effortless and analysis is automatic for most languages, Fast, accurate analysis; enterprise scalability. I would therefore assert that a platform whose memcpy() did anything besides a no-op when given n=0 and valid source/destination pointers was not C-standards-compliant. This 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]. 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. sometimes FP occurs. This rule applies to all null pointers, regardless of which function returned them. Phew, we're agreed here. Asking for help, clarification, or responding to other answers. How do you ensure that a red herring doesn't violate Chekhov's gun? Software project. Is the God of a monotheism necessarily omnipotent? The fact that you can't pass a null (no object) with a reference parameter can be a reason to use a pointer instead. positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. You can use Optional instead. What is the point of Thrower's Bandolier? Find centralized, trusted content and collaborate around the technologies you use most. But even with this, the concerned object it tagged as a possible NullPointerException problem. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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. Trying to understand how to get this basic Fourier Series. SonarJava Version 5.9.2 (build 16552). 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). Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. 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 . We resolved it by adding our tools path in the white list, and repackaging it. Is there a single-word adjective for "having exceptionally strong moral principles"? This topic was automatically closed 7 days after the last reply. A reference to Nothing should never be dereferenced/accessed. The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. Software project. 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]. 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). the Java one). 11 Sep, 2006. extern char _etext; Two null pointers will always be equal to each other. At worst, it could expose debugging information that would be useful to an attacker, or That makes sense. If you call connect() function, it better do the connection, but failing simply because some ptr is NULL is not good behaviour -- failures should . 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. 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. Java Specification Participation Agreement version in use: 2.0. What does it mean that a reference must refer to an object, not a dereferenced null pointer? 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. 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. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. 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. To learn more, see our tips on writing great answers. We. . Just because something is a pointer does not mean you should call delete . Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. it could allow an attacker to bypass security measures. Sonar is ok. 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. All content is copyright protected. Here is our source code: Sign in to download full-size image When you have a variable of non-primitive type, it is a reference to an object. ii. How can this new ban on drag possibly be considered constitutional? We cannot understand how there could be a null pointer exception at the reported line. 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" Is it suspicious or odd to stand by the gate of a GA airport watching the planes? 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 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. The user_data pointer could be invalid in other ways, such as pointing to freed memory. I think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. Search for vulnerabilities resulting from the violation of this rule on the CERT website. A NULL pointer can be dereferenced when signatures are being verified on PKCS7 signed or signedAndEnveloped data. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. But when length of A is 1, the control never reaches the else block. Thanks for contributing an answer to Stack Overflow! When a variable is declared as being a pointer to type void, it is known as a generic pointer. I have a sonar alert on this call minRating.getRatgCaam(). Asking for help, clarification, or responding to other answers. Check whether a String is not Null and not Empty. versions used (SonarQube, Scanner, language analyzer) In Java, a special null value can be assigned to an object reference. If not, this might be a bug. Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2, Sonar false-positive on rule: Null pointers should not be dereferenced, Null Pointer Dereference issue not detected when the pointer is returned by another function. In the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. JCP version in use: 2.6. If malloc() fails, it returns a null pointer that is assigned to c_str. You can use Optional instead. Is there a single-word adjective for "having exceptionally strong moral principles"? Software Engineering Institute
util.regex.Matcher, java - Swing .getParent() . Discover SonarLint SaaS Setup is effortless and analysis is automatic for most languages Discover SonarCloud Self-Hosted Fast, accurate analysis; enterprise scalability Discover SonarQube Secrets ABAP isEmpty(Map map) At best, such an exception will cause abrupt program termination. Which ensures that the chunkdata pointer is valid, but makes no such check to the user_data pointer. Aaron:I suspect we are talking past each other. attacker to bypass security measures. Which @NotNull Java annotation should I use? In particular, ROSE ensures that any pointer returned by malloc(), calloc(), or realloc() is first checked for NULL before being used (otherwise, it is free()-ed). So the SIZE_MAX check was unnecessary. I added an assertion to that compliant code example. 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. Is null check needed before calling instanceof? 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. 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. Trying to understand how to get this basic Fourier Series. 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. Alternate Terms Relationships Interactions/interfaces with C can't use references. 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. Issues Components. Your assertion is not backed by the wording in the standard, nor by common implementer understanding. 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. The alert is related to the sonar rule : Null pointers should not be dereferenced. very old code or C code being worked into c++ may have functions that expect the user to delete the data. This is a feature that we are currently heavily working on to be able to switch off such kind of false positives. SonarQube - Null Pointer Dereference Issue java simonsirak (Simon Sirak) June 14, 2018, 1:18pm 1 Hi! To create a custom null validation method declare an attribute with name ValidatedNotNullAttribute and mark the parameter that is SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. The Clang Static Analyzer already has a checker to find the null pointer dereference in code, however it is not sufficient for higher abstractions such as C++ smart pointers or optionals. The same problem we will have with "Add at least one assertion to this test case." Because a null pointer does not point to a meaningful object, an attempt to dereference(i.e., access the data stored at that memory location) a null pointer usually (but not always) causes a run-time error or immediate program crash. Find centralized, trusted content and collaborate around the technologies you use most. What is null pointer exception in android. When c_str is dereferenced in memcpy(), the program exhibits undefined behavior. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? positive S2637 in SonarQube 6.7.1 LTS, SonarQube for MSBuild not reporting quality issues, getTextContent() through "Null pointers should not be dereferenced". specifies the length of the array for a function. 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. This engine is validating execution paths and checking for non-null values or null-check along the way, exploring all the possibilities. 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. Additionally, if input_str is a null pointer, the call to strlen() dereferences a null pointer, also resulting in undefined behavior. I have checked on multiple . My question is; is my solution incorrect? The problem is that something like %*pbl which reads a bitmask, will save the pointer to the bitmask in the buffer. ncdu: What's going on with this second size column? 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 (?,?,?,?,?,?,?,? When length is zero, it is probably unusable condition for this function. Shouldn't the function check all pointers before dereferencing them or passing them to another function? How can I check before my flight that the cloud separation requirements in VFR flight rules are met? The method isNR(minRating) is a helper method that validate among other things, if the object minRating is null. 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. Then we hit memcpy with length 0. Some Interesting Facts: 1) void pointers cannot be dereferenced. How do I align things in the following tabular environment? It is still a pointer though, to use it you just have to cast it to another kind of pointer first. My below code where I'm calling a stored procedure is giving a null pointer exception. NULL vs Void Pointer - Null pointer is a value, while void pointer is a type. that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. In the code, we check the not nullity with java.util.Objects.nonNull(). Accessing or modifying a null object's field. The standard will simply copy 0 byteswhich is essentially a no-op. When B is null, The control reaches inside the main if block only when length of A is 1. 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. False-positives are pointed out in other SO posts (1 & 2), where nulls are involved across functions and procedures. 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. 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. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? static-code-analysis Please direct comments on this JSR to the Spec Lead (s) Team. NullPointerException is a RuntimeException. And the compliant solution guarantees that the pointer will be valid if the code calls memcpy(). What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). Whoops, you're right. 1 Answer Sorted by: 1 Your code is ok. However there is no portable way to verify that the pointer is valid, other than checking for null. Put a new ResponseEntity is wrong because I won't know what will be the answer for the status of http. sonar-java. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. However, memory allocation > functions such as kstrdup() may fail and returns NULL. PS: I also tried the code in android studio which uses Lint and got no warnings. 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. Issues Components. A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. 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 That noncompliant code example (it's currently the 3rd) came from the Linux kernel, whose source is publicly available. Is there a proper earth ground point in this switch box? In this noncompliant code example, input_str is copied into dynamically allocated memory referenced by c_str. 1 Answer Sorted by: 2 Your code needs to do something about the possible NullPointerException when some exception is caught, because in this scenario the responseDto will be null. I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. I believe in this case, either expression would work. Dereferencing a null pointer results in undefined behavior. 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. 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. assert(!invalid(p)); // or whatever, bool invalid(const void *p) { In my experience, there are reasons to check for a NULL pointer other than dereferencing it. Report False-positive / False-negative [LTS] The new SonarQube LTS is here: SONARQUBE 9.9 LTS, SonarQube - Null Pointer Dereference Issue. Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. This will normally lead to an unhandled error, resulting in a segmentation fault. rev2023.3.3.43278. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? Asking for help, clarification, or responding to other answers. For the time being, I would unfortunately recommend to mark as False Positive the issue. 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>. In some situations, however, dereferencing a null pointer can lead to the execution of arbitrary code [Jack 2007,van Sprundel 2006]. It is useful to have a function with portable interface but platform-dependent implementation: extern bool invalid(const void *); Passing ownership of something also requires pointers. 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. , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow Powered by Discourse, best viewed with JavaScript enabled. Your code needs to do something about the possible NullPointerException when some exception is caught, because in this scenario the responseDto will be null. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. . sonarLint (3.2.) On many platforms, dereferencing a null pointer results in abnormal program termination, but this is not required by the standard. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. There are many ways to resolve this. Does Java have support for multiline strings? 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Null pointers should not be dereferenced. Possible fix: Assign a valid address to the pointer in all branches of the conditional statement.. Pointer can point to dynamically allocated memory. context.RaiseException , (/) I say "theoretical" because I have not successfully produced strings of this length in testing. 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. A reference to null should never be dereferenced/accessed. res.getBody() == null || res.getBody().getServiceResult() == null). Finally my method is returning a response with value of restTemplate. 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). , NPE : null-, . io.NotSerializableException : java. By explicitly teaching the C++ standard class behaviors we can make the Analyzer to find more bugs related to modern C++ code. This solution also ensures that theuser_data pointer is not null. 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. 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). Solution 1, it looks like, today's solution tomorrow's problem. ), 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). See C17 7.1.4p1, which says, in part: Each of the following statements applies unless explicitly stated otherwise in the detailed descriptions that follow: If an argument to a function has an invalid value (such as a value outside the domain of the function, or a pointer outside the address space of the program, or a null pointer, or a pointerto non-modifiable storage when the corresponding parameter is not const-qualified) or a type (after default argument promotion) not expected by a function with a variable number of arguments, the behavior is undefined.
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null pointers should not be dereferenced