Extended Description NULL pointer dereference issues can occur through a number of flaws, including race conditions, and simple programming omissions. To be precise, once length is changed to a size_t and cannot take negative values, it cannot have an invalid value. This sounds indeed like a bug in the flow when an exception is raised. 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" Please direct comments on this JSR to the Spec Lead (s) Team. Many platforms can support testing for those also. 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 Carnegie Mellon University
But no where in that particular idiom would a NULL pointer necessarily be deferenced. New replies are no longer allowed. It's still illegal. The standard will simply copy 0 byteswhich is essentially a no-op. To create a custom null validation method declare an attribute with name ValidatedNotNullAttribute and mark the parameter that is Why do academics stay as adjuncts for years rather than move around? Note that it doesn't know how to check for non-heap, non-stack. 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.. sonarlint, sonarLint (3.2.) Does it just mean failing to correctly check if a value is null? It's a modular system with the . My question is; is my solution incorrect? 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. The null pointer check for writing or dereferencing should be a compiler flag or library setting. My code is GPL licensed, can I issue a license to have my code be distributed in a specific MIT licensed project? 3.7. My below code where I'm calling a stored procedure is giving a null pointer exception. These can be: Invoking a method from a null object. Could I capture, and I would be able to glean much security information from the dump? Provide a self-contained reproducer (zipped project?) sonarLint (3.2.) I suggest that this topic needs to include calloc() and realloc() Refer to Linux man pages online for more enlightenment about malloc(), and friends. EXP34-C is a common consequence of ignoring function return values, but it is a distinct error, and can occur in other scenarios too. (C11, S7.24.2.1). Unfortunately the problem is much more complex, and generally unsolvable within standard C. Consider the following example: There's no way f can check whether x points into valid memory or not. 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 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. () , NPE : null-, . Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? For example the following program doesn't compile. Unlike reference types, pointer types are not tracked by the default garbage . We. int changed to size_t and if size_t parameter's is zero, allocate one word. 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?) Small typo nit: "such as if i t pointed to freed memory" meant to say "if it" instead (removing whitespace). 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. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. 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. https://www.yammer.com/ http://feeds.feedburner.com/office/fmNx Cause we need throw our own Runtime Exception, well-known methods wont help. In the simplest case, this function just returns the result of calling kmalloc. At worst, it could expose debugging information that would be useful to an attacker or it could allow an 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 (?,?,?,?,?,?,?,? Connect and share knowledge within a single location that is structured and easy to search. 3.Null pointers should not be derefer enced/accessed. Linear regulator thermal information missing in datasheet, Identify those arcade games from a 1983 Brazilian music video. Find centralized, trusted content and collaborate around the technologies you use most. Haiku is a free and open-source operating system for PC designed to be binary compatible with the BeOS operating system and embodying the basic ideas of BeOS. Thus we should check > this kstrdup() operation. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? 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. However, memory allocation > functions such as kstrdup() may fail and returns NULL. Mutually exclusive execution using std::atomic? I'd guess null pointers are not valid, even though they point to 0 bytes. I don't need to do this validation again. 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! Pointer members in structs are not checked. Removing the check "exception != null" raises S2259 "Null pointers should not be dereferenced" on "throw exception". It also adds assertions to document that certain other pointers must not be null. But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. 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. Is there a single-word adjective for "having exceptionally strong moral principles"? As for copy vs pointer/reference - it depends. Thanks for the feedback. In the complaint version, I like to make source code checking a little quicker by putting parenthesizes around arguments to |= or &= as. Reports. It is useful to have a function with portable interface but platform-dependent implementation: extern bool invalid(const void *); We resolved it by adding our tools path in the white list, and repackaging it. 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. Null pointers should not be dereferenced. positive S2637 in SonarQube 6.7.1 LTS, Sonar false positive, "change condition so that it does not always evaluate to true. isEmpty(Map map) Making statements based on opinion; back them up with references or personal experience. Trying to understand how to get this basic Fourier Series. @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. SONAR, SONARSOURCE, SONARLINT, SONARQUBE and SONARCLOUD are trademarks of SonarSource S.A. All other trademarks and copyrights are the property of their respective owners. Trying to understand how to get this basic Fourier Series. Sonar detects that res.getBody() can be null when you do the check res.getBody()==null. Styling contours by colour and by line thickness in QGIS. The issue of passing n=0 to memcpy() is distinct from null or invalid pointers. In this case, the difference is the assumption thatmalloc() always returns non-nullfor the second NCCE, whereas the first NCCE has themalloc() abstracted away. I doubt that "length" of zero is a valid parameter, and although there no copy, but we see memory allocation. Asking for help, clarification, or responding to other answers. 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. Staging Ground Beta 1 Recap, and Reviewers needed for Beta 2. ucsi->connector gets dereferenced by both ucsi_connector_change() and ucsi_resume(), both check for ucsi->connector being NULL in case ucsi_init() has not finished yet; or in case ucsi_init() has failed. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. In multithreaded programs, null pointer dereferences can violate cache coherency policies and can cause resource leaks. When B is null, The control reaches inside the main if block only when length of A is 1. Thanks for contributing an answer to Stack Overflow! What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? "After the incident", I started to be more careful not to trip over things. Doing so will cause a NullPointerException to be thrown. 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. The null concept refers to the idea that a pointer can hold a special value that is not equal to another pointer. I'd guess WG14 has considered these questions, but I haven't until now :). At best, such an exception will cause abrupt program termination. Now, you can find the list of whitelisted methods here. SonarQube Version 6.7.2 (build 37468) All content is copyright protected. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Passing a null pointer tomemcpy() would produce undefined behavior, even if the number of bytes to copy were 0. When length is zero, it is probably unusable condition for this function. The only potential null is the return value of 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]. This compliant solution ensures that the pointer returned by png_malloc() is not null. SonarLint: A "NullPointerException" could be thrown; "getBody()" can return null. This sounds indeed like a bug in the flow when an exception is raised. How can I check before my flight that the cloud separation requirements in VFR flight rules are met? Whats the grammar of "For those whose stories they are"? - the incident has nothing to do with me; can I use this this way? Description The program can potentially dereference a null pointer, thereby raising a NullPointerException. 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. 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. What Is the Difference Between 'Man' And 'Son of Man' in Num 23:19? The solution that I recommend is not work with null returns or variables on Java, try to avoid it. 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. 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. Is it plausible for constructed languages to be used to affect thought and control or mold people towards desired outcomes? 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.