null pointers should not be dereferenced

When length is zero, it is probably unusable condition for this function. Solution 1, it looks like, today's solution tomorrow's problem. Calls to extension methods are not reported because they can still operate on null values. 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]. What is the point of Thrower's Bandolier? Small typo nit: "such as if i t pointed to freed memory" meant to say "if it" instead (removing whitespace). I'd guess null pointers are not valid, even though they point to 0 bytes. Do "superinfinite" sets exist? I suggest that this topic needs to include calloc() and realloc() Refer to Linux man pages online for more enlightenment about malloc(), and friends. All rights are expressly reserved. Is there a single-word adjective for "having exceptionally strong moral principles"? NullPointerException is thrown when program attempts to use an object reference that has the null value. In some situations, however, dereferencing a null pointer can lead to the execution of arbitrary code [Jack 2007,van Sprundel 2006]. Not the answer you're looking for? Since SIZE_MAX represents the largest possible object, the largest possible string would then be SIZE_MAX-1 characters long (excluding '\0'). Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. You need to benchmark. Automated Detection Null pointer dereferences can happen in path-dependent ways. But even with this, the concerned object it tagged as a possible NullPointerException problem. To learn more, see our tips on writing great answers. In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. Void pointers cannot be dereferenced as any other pointer. Key here (explains table format and definitions), EXP34-C = Union( CWE-690, list) where list =. 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. Additionally, if input_str is a null pointer, the call to strlen() dereferences a null pointer, also resulting in undefined behavior. Thanks for your relpy. 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. 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 Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. What is generic pointer? 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. Correct; a null pointer is not a valid pointer for the C library functions. 412-268-5800, If an argument to a function has an invalid value (such as a value outside the domain of the function, or a pointer outside the address space of the program, or a null pointer, or a pointer. Im very new to sonar, is there a way to add methods to the whitelist? I believe in this case, either expression would work. Reports. So Bar might not be initialized but then the last line of your example should not be evaluated in this case. Asking for help, clarification, or responding to other answers. In C, dereferencing a null pointer is undefined behavior. raiseException() return, Sonar Things go fine now. In the code, we check the not nullity with java.util.Objects.nonNull(). This will normally lead to an unhandled error, resulting in a segmentation fault. 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 . Off by one error: It is the third example. This code also violates ERR33-C. Detect and handle standard library errors. This sounds indeed like a bug in the flow when an exception is raised. Is there a proper earth ground point in this switch box? 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. What is pointed to should only be deleted if it was created with new. We seem to have a false positive for "Null pointers should not be dereferenced" - squid:S2259. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? I suppose there is a question of "Is a pointer that points to 0 bytes valid?" In the meantime, Im locking this thread. 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. Trying to understand how to get this basic Fourier Series. Is it possible to create a concave light? But no where in that particular idiom would a NULL pointer necessarily be deferenced. (/). I say "theoretical" because I have not successfully produced strings of this length in testing. 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 (?,?,?,?,?,?,?,? 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. Please explain: Without this, we wont be able to help you. For the time being, I would unfortunately recommend to mark as False Positive the issue. Asking for help, clarification, or responding to other answers. A null pointer in this position causes the read system call to fail with -EINVAL ("Invalid argument"). Then the reading of the buffer via bstr_printf() will then look at the pointer to process the final output. But when length of A is 1, the control never reaches the else block. . This is a matter of style, and also following code walkthrough. 5.2 Part 2 Sometimes a helper function is de ned to perform the memory allocation. 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. It also reinforces the notion to the reader that any time you see arithmetic in an allocation expression, you need to think about corner-cases. Is there a solution to add special characters from software and how to do it, Acidity of alcohols and basicity of amines. I would also guess that pointers that point to the one-past-the-end of an array are also invalid. Check whether a String is not Null and not Empty. This issues is displayed by SonarQube. As for copy vs pointer/reference - it depends. 11 Sep, 2006. 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 Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. context.RaiseException , (/) That is why I explicitly check for this in my attempted solution. Basically, yes. 1 Answer Sorted by: 1 Your code is ok. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 1 Null pointers should not be dereferenced @CheckForNull String getName(){.} best, such an exception will cause abrupt program termination. Alternate Terms Relationships Styling contours by colour and by line thickness in QGIS. Possible fix: Assign a valid address to the pointer in all branches of the conditional statement.. Pointer can point to dynamically allocated memory. This code also violates ERR33-C. Detect and handle standard library errors. 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 4. Dereferencing a null pointer can lead to a denial of service. How do I align things in the following tabular environment? rev2023.3.3.43278. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Interactions/interfaces with C can't use references. Shouldn't the function check all pointers before dereferencing them or passing them to another function? The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? Hi Andreas, Thanks for the feedback. Privacy Policy, Detect issues in your GitHub, Azure DevOps Services, Bitbucket Cloud, GitLab repositories. ii. Extended Description NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions. 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 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). I think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. This rule applies to all null pointers, regardless of which function returned them. Batch split images vertically in half, sequentially numbering the output files, Difficulties with estimation of epsilon-delta limit proof, Minimising the environmental effects of my dyson brain. Its purpose is to serve as a special value for a pointer that could indicate a special condition in your program. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. The problem is that something like %*pbl which reads a bitmask, will save the pointer to the bitmask in the buffer. assert(!invalid(p)); // or whatever, bool invalid(const void *p) { 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. 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. Find centralized, trusted content and collaborate around the technologies you use most. You can use Optional instead. In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. , . The user_data pointer could be invalid in other ways, such as pointing to freed memory. A reference to Nothing should never be dereferenced/accessed. int changed to size_t and if size_t parameter's is zero, allocate one word. Essentially, this code and the previous dereference disagree as to whether this value is allowed to be null. 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. https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx SonarJava. The expected result here is solve the issue with sonarqube. Ticket opened : Thanks a lot for the minimalized reproducer ! It also uses the unsigned type size_t to pass the length parameter, ensuring that negative values are not passed to func(). () False-positives are pointed out in other SO posts (1 & 2), where nulls are involved across functions and procedures. However, memory allocation > functions such as kstrdup() may fail and returns NULL. We can get a reference to point to null in the following ways: "uninitialized" reference type variables variables which are initialized with nulls and are assigned their real value afterward. But what exactly does it mean to "dereference a null pointer"? 3.7. At best, such an exception will cause abrupt program termination. // <------- 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. Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. SonarJava Version 5.9.2 (build 16552). Instead use String.valueOf (object). Thanks for contributing an answer to Stack Overflow! How to use Slater Type Orbitals as a basis functions in matrix method correctly? Consider the following scenario: you are asked to create a Java class MetaDisplay that contains a static void printTable(String r) method. Null pointers should not be dereferenced. 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. To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. Does a summoned creature play immediately after being summoned by a ready action? I added a comment to explain that SIZE_MAX is the limit of size_t. A pointer is simply a variable that contains a memory address. Note that it doesn't know how to check for non-heap, non-stack. NullPointerException is a RuntimeException. 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. 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. Which @NotNull Java annotation should I use? Cause we need throw our own Runtime Exception, well-known methods wont help. Is there a proper earth ground point in this switch box? sonarqube 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. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? util.regex.Matcher, java - Swing .getParent() . Then we hit memcpy with length 0. 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. 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. Thered be huge value in jumping onto the latest version of the ecosystem (notably SonarQube), and benefit from all latest analyzers (e.g. So no checking of the length is necessary (besides preventing integer overflow, which the compliant solution does). By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Appropriate typecasting is necessary. Provide a self-contained reproducer (zipped 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]. I suppose we can check that that is not null, but we cannot check that it is valid (in any portable way). We resolved it by adding our tools path in the white list, and repackaging it. Dereferencing a null pointer results in undefined behavior. 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. - the incident has nothing to do with me; can I use this this way? What can a lawyer do if the client wants him to be acquitted of everything despite serious evidence? I have a sonar alert on this call minRating.getRatgCaam(). It's still illegal. Doing so will at best cause abrupt program termination, without the That makes sense. 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. 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). Status: Dormant. It means this is illegal: T* p = nullptr; T& r = *p; // illegal NOTE: Please do not email us saying the above works on your particular version of your particular compiler. SonarQube - Null Pointer Dereference Issue java simonsirak (Simon Sirak) June 14, 2018, 1:18pm 1 Hi! The solution that I recommend is not work with null returns or variables on Java, try to avoid it. sonarlint, sonarLint (3.2.) We really appreciate your help. can have the value zero on a call to that function. Search for vulnerabilities resulting from the violation of this rule on the CERT website. IMHO, the rule title should be changed to something less general. I'd guess WG14 has considered these questions, but I haven't until now :). To subscribe to this RSS feed, copy and paste this URL into your RSS reader. 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 reference to null should never be dereferenced/accessed. This is a feature that we are currently heavily working on to be able to switch off such kind of false positives. IDE extension that lets you fix coding issues before they exist! Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. http://blog.llvm.org/2011/05/what-every-c-programmer-should-know_14.html. When a variable is declared as being a pointer to type void, it is known as a generic pointer. Dereferencing > this null pointer may cause the kernel go wrong. It does not point to any area of memory. https://stackoverflow.com/questions/47534436/, https://stackoverflow.com/questions/47534436/, java - Jenkins groovy : Error: java. Put a new ResponseEntity is wrong because I won't know what will be the answer for the status of http. Does it just mean failing to correctly check if a value is null? Making statements based on opinion; back them up with references or personal experience. How can we prove that the supernatural or paranormal doesn't exist? But when length of A is 1, the control never reaches the else block. And fwstr > is dereferenced in the following codes. If you try to access any member variables or methods with that variable, you are trying to dereference it. Should trycatch go inside or outside a loop? The article easily misleads the reader into believeing that ensuring pointer validity boils down to checking for pointer being not equal to NULL. This solution also ensures that theuser_data pointer is not null. Connect and share knowledge within a single location that is structured and easy to search. 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. Please direct comments on this JSR to the Spec Lead (s) Team. Here is our source code: Sign in to download full-size image When c_str is dereferenced in memcpy(), the program exhibits undefined behavior. , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow Find centralized, trusted content and collaborate around the technologies you use most. The fact that you can't pass a null (no object) with a reference parameter can be a reason to use a pointer instead. What is a serialVersionUID and why should I use it? ), 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. 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. Carnegie Mellon University Trying to understand how to get this basic Fourier Series. How to tell which packages are held back due to phased updates. Explain about call by reference with an . I added an assertion to that compliant code example. vegan) just to try it, does this inconvenience the caterers and staff? Asking for help, clarification, or responding to other answers. 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 On many platforms, dereferencing a null pointer results inabnormal program termination, but this is not required by the standard. What sort of strategies would a medieval military use against a fantasy giant? 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. If you preorder a special airline meal (e.g. LANG.MEM.NPDLANG.STRUCT.NTADLANG.STRUCT.UPD, Null pointer dereferenceNull test after dereferenceUnchecked parameter dereference, Can detect violations of this rule. We. 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?) very old code or C code being worked into c++ may have functions that expect the user to delete the data. ncdu: What's going on with this second size column? Goal Sonar is ok. rev2023.3.3.43278. How do I align things in the following tabular environment? Connect and share knowledge within a single location that is structured and easy to search. 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). And if there is no pointer_default declaration, then the default default is ref. I am a student implementing stack with singly linked list using C, following a book called Fundamentals of Data Structures in C.. Trying to understand how to get this basic Fourier Series. We cannot understand how there could be a null pointer exception at the reported line. IDE extension that lets you fix coding issues before they exist! Not the answer you're looking for? Ah, gotcha. PS: I also tried the code in android studio which uses Lint and got no warnings. This compliant solution ensures that the pointer returned by png_malloc() is not null. At worst, it could expose debugging information that would be useful to an attacker, or There is no guarantee that subsequent invocations are returning the same value, thats why issue is raised. 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. In C/C++ speak, 'dereferencing' simply means getting the object that a pointer . 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. 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. attacker to bypass security measures. Java Specification Participation Agreement version in use: 2.0. 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.

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