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. 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. Key here (explains table format and definitions), EXP34-C = Union( CWE-690, list) where list =. 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]. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? 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. 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). Many platforms can support testing for those also. The alert is related to the sonar rule : Null pointers should not be dereferenced. The correct idiom is to only allocate storage if the pointer is currently NULL. Why do academics stay as adjuncts for years rather than move around? Using Kolmogorov complexity to measure difficulty of problems? ability to run any cleanup processes. This cross-file approach analysis can be quite resource-consuming, and we are not ready to openly enable the feature. 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). Avoid Returning null from Methods. Making statements based on opinion; back them up with references or personal experience. Phew, we're agreed here. 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. 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. I added an assertion to that compliant code example. very old code or C code being worked into c++ may have functions that expect the user to delete the data. We. You can compare a pointer with NULL to test for the special condition. validated for null in your method declaration with it: 2008-2023 SonarSource S.A., Switzerland. The user_data pointer could be invalid in other ways, such as pointing to freed memory. What is pointed to should only be deleted if it was created with new. My question is; is my solution incorrect? I have checked on multiple . Just because something is a pointer does not mean you should call delete . 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. 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). If you preorder a special airline meal (e.g. Obviously the value of that pointer could have changed since the . It also adds assertions to document that certain other pointers must not be null. Is there a single-word adjective for "having exceptionally strong moral principles"? 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. The solution that I recommend is not work with null returns or variables on Java, try to avoid it. With their flexibility, void pointers also bring some constraints. In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. 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. sonarLint (3.2.) That is, sets equivalent to a proper subset via an all-structure-preserving bijection. 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. I could've fixed this by changing else to else if (B != null && B.length == 1), but doing so rewards me with warning "condition(B != null && B.length == 1) is always true". 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. This engine is validating execution paths and checking for non-null values or null-check along the way, exploring all the possibilities. Isn't easier just to check valid range of length? All rights are expressly reserved. context.RaiseException , (/) Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. null(java.lang.NullPointerException) . Thanks for your relpy. If malloc() fails, it returns a null pointer that is assigned to c_str. For example the following program doesn't compile. Currently I'm working with SonarQube solving issues but I'm facing a trouble to how handle null pointers that shouldn't be dereferenced. How to deal with "java.lang.OutOfMemoryError: Java heap space" error? A reference to Nothing should never be dereferenced/accessed. Pittsburgh, PA 15213-2612
On many platforms, dereferencing a null pointer results in abnormal program termination, but this is not required by the standard. It looks like a logic bug, which can cause a memory leaking. To learn more, see our tips on writing great answers. 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. 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. public boolean isNameEmpty() { return getName().length() == 0; // Noncompliant; the result of getName() could be null, but isn't null-checked } . Correct; a null pointer is not a valid pointer for the C library functions. 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. I say "theoretical" because I have not successfully produced strings of this length in testing. 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. @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. A reference to null should never be dereferenced/accessed. This topic was automatically closed 7 days after the last reply. void *pointerVariableName = NULL; Since they are very general in nature, they are also known as generic pointers. 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. 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 null pointer stores a defined value, but one that is defined by the environment to not be a valid address for any member or object. 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. 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. Could I capture, and I would be able to glean much security information from the dump? Asking for help, clarification, or responding to other answers. ", Eclipse - Sonar S2629 possible false positive with new String, SonarQube null pointers should not be dereferenced on try/catch, getTextContent() through "Null pointers should not be dereferenced". ), 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). The issue is: memcpy() and friends do not explicitly state that a null pointer is a valid pointer value, even if the number of bytes to copy is 0. There are other problems with this code, as is noted in the rule. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? Note that it doesn't know how to check for non-heap, non-stack. 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. PS: I also tried the code in android studio which uses Lint and got no warnings. return p == NULL || (char *)p < &_etext; Even if the object is null in this case, it will not give an exception and will print ' null ' to the output stream. A pointer to null (the 0 memory address) should never be dereferenced/accessed. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to bypass security measures. I don't need to do this validation again. I think "res.getBody() == null" checks null first so it should go to return line, not reach to next if condition. }. Dereferencing a null pointer results in undefined behavior. Is there a proper earth ground point in this switch box? Automated Detection Null pointer dereferences can happen in path-dependent ways. 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?) 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. 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 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. If you try to access any member variables or methods with that variable, you are trying to dereference it. I'd guess null pointers are not valid, even though they point to 0 bytes. But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. All content is copyright protected. NULL vs Void Pointer - Null pointer is a value, while void pointer is a type. However, memory allocation > functions such as kstrdup() may fail and returns NULL. 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. At Trying to understand how to get this basic Fourier Series. 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. raiseException() return, Sonar This code also violates ERR33-C. Detect and handle standard library errors. ), 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. Does a summoned creature play immediately after being summoned by a ready action? 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. At this point we define size as strlen(input_str) + 1. At worst, it could expose debugging information that would be useful to an attacker, or it could allow an attacker to . Whoops, you're right. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Note that 7.1.4 explicitly states that a null pointer is not a valid pointer argument. To learn more, see our tips on writing great answers. Maybe one of these methods is already doing what your methods is doing, and could be considered as replacement. Share Improve this answer Follow answered Oct 5, 2017 at 16:27 assert(!invalid(p)); // or whatever, bool invalid(const void *p) { In order to fix this, just do the following: BodyType body=res.getBody (); if (body == null || body.getServiceResult () == null) { return; } You can then even reuse body after that. Alternate Terms Relationships 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]. 11 Sep, 2006. Void pointers cannot be dereferenced as any other pointer. And the semantics, as I said, are different.
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