There are other problems with this code, as is noted in the rule. public boolean isNameEmpty() { return getName().length() == 0; // Noncompliant; the result of getName() could be null, but isn't null-checked } . A common memory-leak idiom, is reallocating storage and assigning its address to a pointer that already points to allocated storage. This solution also ensures that theuser_data pointer is not null. In C, dereferencing a null pointer is undefined behavior. Essentially, this code and the previous dereference disagree as to whether this value is allowed to be null. Optimizers are optimizing based on this latitude and have been for years. Find centralized, trusted content and collaborate around the technologies you use most. In the code, we check the not nullity with java.util.Objects.nonNull(). Does it just mean failing to correctly check if a value is null? rev2023.3.3.43278. Thanks, David! But when length of A is 1, the control never reaches the else block. 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 This is a matter of style, and also following code walkthrough. 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 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). Do "superinfinite" sets exist? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. ii. We cannot understand how there could be a null pointer exception at the reported line. 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. 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. You're in a company-managed project. NullPointerException is thrown when program attempts to use an object reference that has the null value. Issues Components. 4. Appropriate typecasting is necessary. Which @NotNull Java annotation should I use? When exploring such methods, the engine then deduces behaviors regarding null-checking (among other things). 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 IDE extension that lets you fix coding issues before they exist! 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. Here is our source code: Sign in to download full-size image Thanks for contributing an answer to Stack Overflow! On many platforms, dereferencing a null pointer results in abnormal program termination, but this is not required by the standard. which would allow us to systematically observe what you are having. Iflengthhas the value1, the addition yields 0, and png_malloc() subsequently returns a null pointer, which is assigned to chunkdata. For example the following program doesn't compile. 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. We. Key here (explains table format and definitions), EXP34-C = Union( CWE-690, list) where list =. Solution 1, it looks like, today's solution tomorrow's problem. Can you please start a new thread and be more explicit about the issue you are observing. ncdu: What's going on with this second size column? (/). 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. There is a missing check for the return value from . Why does the second compliant example permit using possibly-null pointers? If you write [ref], then a null pointer is not allowed, but if you write [unique], then a null pointer is permitted. These can be: Invoking a method from a null object. That interpretation of the standard is not supported universally. Software Engineering Institute
Rule squid:S2259 is based on a Symbolic Execution (SE) engine. Please direct comments on this JSR to the Spec Lead (s) Team. io.NotSerializableException : java. Accessing or modifying a null object's field. It also adds assertions to document that certain other pointers must not be null. I believe that dereferencing NULL should not crash the system, should not allow a write to a NULL pointer area, but should always set errno, If I am a hacker, could I trap a null failure that would force a memory dump. 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]. Reports. The same problem we will have with "Add at least one assertion to this test case." You can use Optional instead. I have checked on multiple . Software project. To learn more, see our tips on writing great answers. Because null pointer dereferencing is undefined behavior, the compiler (GCC in this case) can optimize away the if (!tun) check because it is performed after tun->sk is accessed, implying that tun is non-null. The libpng library allows applications to read, create, and manipulate PNG (Portable Network Graphics) raster image files. To learn more, see our tips on writing great answers. 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. 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. As for copy vs pointer/reference - it depends. If you call connect() function, it better do the connection, but failing simply because some ptr is NULL is not good behaviour -- failures should . When length is zero, it is probably unusable condition for this function. In the first compliant example it's useless to do allocation if the essential pointer user_data is NULL. This latter use of pointers is a combined boolean/satellite: the pointer being non-null indicates "I have this sister object", and it provides that object. 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 does "Could not find or load main class" mean? My below code where I'm calling a stored procedure is giving a null pointer exception. Passing a null pointer tomemcpy() would produce undefined behavior, even if the number of bytes to copy were 0. 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. 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. Its purpose is to serve as a special value for a pointer that could indicate a special condition in your program. And if there is no pointer_default declaration, then the default default is ref. , RemoteContext new ExceptionType() RemoteContext , SonarLintJava (), java - sonarLint "Null pointers should not be dereferenced (squid:S2259)"Stack Overflow In C# and Java, all reference types can point to null. This sounds indeed like a bug in the flow when an exception is raised. One could argue that all code examples would be redundant with the first pair. Now (sonarqube java analyzer version 4.3.0.7717) it's supported and works fine. Connect and share knowledge within a single location that is structured and easy to search. The user_data pointer could be invalid in other ways, such as pointing to freed memory. At worst, it could expose debugging information that would be useful to an attacker, or specifies the length of the array for a function. Does a summoned creature play immediately after being summoned by a ready action? Find centralized, trusted content and collaborate around the technologies you use most. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? The result of calling such a helper function should be . When and how should I use a ThreadLocal variable? 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. Just because something is a pointer does not mean you should call delete . The standard will simply copy 0 byteswhich is essentially a no-op. How can we prove that the supernatural or paranormal doesn't exist? NULL vs Uninitialized pointer - An uninitialized pointer stores an undefined value. The problem is that something like %*pbl which reads a bitmask, will save the pointer to the bitmask in the buffer. When you have a variable of non-primitive type, it is a reference to an object. We really appreciate your help. If that variable hasn't had a reference assigned, it's a null reference, which (for internal/historical reasons) is referred to as a null pointer. Recovering from a blunder I made while emailing a professor. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. Sonar is ok. context.RaiseException . We can see that at obj.run(), obj can not be null, but is pointed out by Sonar. Off by one error: It is the third example. Are there tables of wastage rates for different fruit and veg? All content is copyright protected. , NPE : null-, . 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. Trying to understand how to get this basic Fourier Series. Please explain: Without this, we wont be able to help you. 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. The null pointer check for writing or dereferencing should be a compiler flag or library setting. This sounds indeed like a bug in the flow when an exception is raised. How can we prove that the supernatural or paranormal doesn't exist? In the meantime, Im locking this thread. can have the value zero on a call to that function. (In contrast, the case of passing 0 bytes to malloc is addressed in C11.) LANG.MEM.NPDLANG.STRUCT.NTADLANG.STRUCT.UPD, Null pointer dereferenceNull test after dereferenceUnchecked parameter dereference, Can detect violations of this rule. IMHO, the rule title should be changed to something less general. Sonar is ok. Sonar can't determine that the helper method did the null validation. 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). After that, you call res.getBody() again. attacker to bypass security measures. Im having trouble understanding your problem. This issues is displayed by SonarQube. Asking for help, clarification, or responding to other answers. But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. Obviously the value of that pointer could have changed since the . Some Interesting Facts: 1) void pointers cannot be dereferenced. Why does Mister Mxyzptlk need to have a weakness in the comics? 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. (C11, S7.24.2.1). 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. isEmpty(Collection collection) positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. Powered by Discourse, best viewed with JavaScript enabled. So the SIZE_MAX check was unnecessary. So, this code should address the Sonar problem: You can also eliminate the null check using Optional
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