coverity null pointer dereference

uint64_t *var1 = malloc(sizeof(uint64_t)); /* Allocate memory for one uint64_t on the heap and set var1 to point at it */. But the problem also exists in the compliant version, so I'm not so sure that it's really compliant. Fixed by setting name to Oh joy. 2012-09-11. Do not use a null in a case where an object is required, https://gcc.gnu.org/gcc-4.9/porting_to.html, ARR30-C. Do not form or use out-of-bounds pointers or array subscripts, Reconsidering pointer dereferences before null pointer checks (with SmPL), understand the source code search pattern, One of the Coccinelle software maintainers expressed opposite development views today, https://stackoverflow.com/questions/25725286/does-taking-address-of-member-variable-through-a-null-pointer-yield-undefined-be, 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. Standing by. int changed to size_t and if size_t parameter's is zero, allocate one word. This information is often useful in understanding where a weakness fits within the context of external information sources. So the SIZE_MAX check was unnecessary. We should Zoom if you wish to talk more. The null pointer check for writing or dereferencing should be a compiler flag or library setting. This solution also ensures that theuser_data pointer is not null. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase. This vulnerability is capable. He also rips off an arm to use as a sword, Canadian of Polish descent travel to Poland with Canadian passport, assertions usually only apply at debug-time (as I was recently reminded with a runtime crash in a release build that made no sense after all, I have assertion safety everywhere, right?). 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. This code will definitely crash due to a null pointer dereference in certain cases. <, [REF-1032] "Null Reference Creation and Null Pointer Dereference". extern char _etext; Correct; a null pointer is not a valid pointer for the C library functions. This check identifies such situation by checking all possible paths where such NULL dereferences can occur. Network monitor allows remote attackers to cause a denial of service (crash) via a malformed Q.931, which triggers a null dereference. Improper Check for Unusual or Exceptional Conditions, Unchecked Return Value to NULL Pointer Dereference, Memory Allocation with Excessive Size Value, Improperly Controlled Sequential Memory Allocation, OWASP Top Ten 2004 Category A9 - Denial of Service, CERT C Secure Coding Standard (2008) Chapter 4 - Expressions (EXP), CERT C Secure Coding Standard (2008) Chapter 9 - Memory Management (MEM), CERT C++ Secure Coding Section 03 - Expressions (EXP), CERT C++ Secure Coding Section 08 - Memory Management (MEM), SFP Secondary Cluster: Faulty Pointer Use, SEI CERT Oracle Secure Coding Standard for Java - Guidelines 02. (where the weakness is a quality issue that might indirectly make it easier to introduce security-relevant weaknesses or make them more difficult to detect). "Signpost" puzzle from Tatham's collection. . Only irrelevant information has been removed. What does 'They're at four. 2005. Connect and share knowledge within a single location that is structured and easy to search. Did the drapes in old theatres actually say "ASBESTOS" on them? FORWARD_NULL. 0->member is undefined behavior. Unexpected uint64 behaviour 0xFFFF'FFFF'FFFF'FFFF - 1 = 0? 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. CalebFenton/simplify. If you are working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the if statement; and unlock when it has finished. 0 is a valid value as far as memcpy() is concerned, and malloc() has special language concerning malloc(0). I would never have thought of looking at this piece of code if coverity hadn't found it. Each call of the impacted function may consumes many bytes (it's a file path). VM {} is NOT a viable candidate for solving affinity group violation situation. I see coverity defect with bold/italic code. Do you find another previous clarification approach interesting and helpful? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, Asside - I would suggest initialising your pointers to, It's impossible to tell from that code whether. Right? Would you become interested in a related clarification approach for a discussion topic like . rev2023.5.1.43405. Software Engineering Institute To learn more, see our tips on writing great answers. Synopsys, Inc. | Policy Statement | Contact. It does not give the pointer a new value. When c_str is dereferenced in memcpy(), the program exhibits undefined behavior. How to force Unity Editor/TestRunner to run at full speed when in background? Allocated memory leaked in several cases. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Would such an aspect be influenced in any ways if the address of operator would be applied around similar expressions? Thanks! Making statements based on opinion; back them up with references or personal experience. If the operand has type "type", the result has type "pointer to type". 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. It worked normally, but sometimes devices had cryptic types. FWIW the pointer arithmetic is also invalid because p1 does not point to valid memory, so you scan't just say something like, That code does not violate th is rule, but it violates ARR30-C. Do not form or use out-of-bounds pointers or array subscripts. The platform is listed along with how frequently the given weakness appears for that instance. 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. I'll add that right now, but I feel it's pointless, since it will only clutter up the question. How to remove elements from a generic list while iterating over it? Your assertion is not backed by the wording in the standard, nor by common implementer understanding. with solve of this bug problems have gone. 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). If a user supplies a malformed request or violates the client policy, the Do method can return a nil response and a non-nil err. If an invalid value has been assigned to the pointer, the behavior of the unary * operator is undefined.115). More specific than a Base weakness. Which ability is most related to insanity: Wisdom, Charisma, Constitution, or Intelligence? This fixed weird behaviour that was really hard to find. Thus I became a bit more curious about involved technical details. Relatively low, but also relatively hilarious - someone decided to "shut up" a GCC warning in 2006 by putting parentheses around an assignment used as a truth value, but misplaced Impact is low, just wanted to commend you! <, [REF-18] Secure Software, Inc.. "The CLASP Application Security Process". VM {} is a viable candidate for solving affinity group violation situation. And in this case, there is no pointed-to data. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. Possibly Clang/LLVM may choose to always return a valid value for &NULL->member. 565), Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI. Find centralized, trusted content and collaborate around the technologies you use most. and Gary McGraw. that we haven't considered here: I'd guess null pointers are not valid, even though they point to 0 bytes. What's the cheapest way to buy out a sibling's share of our parents house if I have no cash and want to pay less than the appraised value? What's the rationale for null terminated strings? Either the check against null is unnecessary, or there may be a null pointer dereference. The different Modes of Introduction provide information about how and when this weakness may be introduced. Isn't easier just to check valid range of length? In Coverity, FORWARD_NULL reports defects when there are enough evidences to be sure the null access will (can) happen. * @return a list of vms which are candidates for migration What were the most popular text editors for MS-DOS in the 1980s? It even looked as a false positive at first. Found logically dead code that would never have been accessed. When length is zero, it is probably unusable condition for this function. Dereferencing a null pointer always results in undefined behavior and can cause crashes. What is this brick with a round back and a stud on the side used for? The above check can't hurt, as I guess you could have a system with a 32-bit size_t that had a ton of memory and had some crazy banking/selector scheme with pointers. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. The idea is not to guarantee validity, but to catch a substantial number of problems that could occur. Identify all variables and data stores that receive information from external sources, and apply input validation to make sure that they are only initialized to expected values. Null pointer dereferences. First if executes for cond1 and else executes for cond2.. Only one of them could be true at a time. Hence the error. Why does the second compliant example permit using possibly-null pointers? I'd really love to know why I'm being downvoted. In some situations, however, dereferencing a null pointer can lead to the execution of arbitrary code [Jack 2007,van Sprundel 2006]. @HemantBhargava - you may know that, but the code you have shown us does not ensure that. Can this be fixed if I reassign the *var1 to NULL again.

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