11/4/2023 0 Comments Integer overflow in expressionBut the following calculated fields areĪctual_asp_loc - Decimal(38,4),net_sales_qty - Double(15), The followingĮxpression in Expression Transformation and the data type of columns in Overflow error in Expression Error in Transformation. I guess it's best that I rewrite my logic in a new check.īut well I have the feeling it could take a couple of days before I have something new.The rows are skipped while data loading into target table because of Integer Int error_string_size = (size_t) print_count + 1 // = LIBCERROR_MESSAGE_MAXIMUM_SIZE ) Next_message_size = (size_t) ( print_count + 1 ) Next_message_size = LIBCERROR_MESSAGE_MAXIMUM_SIZE If( next_message_size >= LIBCERROR_MESSAGE_MAXIMUM_SIZE ) Size_t next_message_size = LIBCERROR_MESSAGE_INCREMENT_SIZE #define LIBCERROR_MESSAGE_MAXIMUM_SIZE 4096 #define LIBCERROR_MESSAGE_INCREMENT_SIZE 64 The only flag I would consider though if the -fwarpv as that defines the concrete semantics. I don't think we should depend on implementation details. ![]() In a path sensitive way, we will always suffer from the limitations of the constraint solver. The given value might get constant folded and get the comparison/branch optimized away. You can never be sure if a given function gets inlined or not, thus the context does matter for compiler optimizations. I hope to have some new code to show soon. Sorry I don't make much progress right now. The current warning message is unacceptable and it must be clarified. is undefined" without explaining why) we should probably silence those instead because it's clear that we can't explain what's going on. Also in other checks there's a bailout path that produces generic diagnostics ("the result. In this new check both operands should be tracked with visitors. Not necessarily a new checker but bug reports from this checker are already lacking a lot of information. Thanks for all comments I feel I will remake this. The patch I provided so far was only a proof of concept. I wouldn't be comfortable enabling it by default without a much more careful evaluation (than a single lit test). ![]() whenever the optimizer can see that there is overflow and has an opportunity to destroy the code. I'd rather also flag more complex examples. Yeah I can't reproduce that with latest gcc/clang neither. Should I add any other flags? Or it is version specific? Therefore I suggest you can do a similar check with the ASTMatcher, since the and and or conjunctions will be removed in the CFG.īTW, I cannot optimize function f to returning zero directly with GCC-10.2.1 and Clang-10.0.1 under -O3. Otherwise, it will be computed during runtime. the result should be determinable literally during compilation. Condition 0x7ffffff0 < x will assume x to be, then x + 32 will be evaluated to which will make the check return true.īut for the example you mentioned, I prefer implementing this check with a coding style checker for Clang-Tidy, although the integer overflow checker in the CSA is also necessary.Īs the evaluation result potentially conflicts with the literal arithmetical result, reporting directly this conflict condition expression would be easier for programmers to diagnostic the code.īesides, as far as I am thinking, the compiler optimizes the expression as it is literally inferable, i.e. ![]() Currently, in the CSA, the symbolic execution engine will return true for this function. ![]() There is no need to report this problem all the time. Or maybe it would be no longer a problem if you implement this in a checker, but as a non-fatal error it is, you can just leave the overflowed value as it is, and report the problem only without terminating the symbol execution on this path. Or it can be the Unknown SVal, but rather than the Undefined SVal, as the Undefined SVal is used to represent what is read from an uninitialized variable.īut I do not favour the Unknown solution, as it could also trigger other problems in the engine, just as what has been mentioned by steakhal. Therefore I suggest the computed value should be "the exact value computed from the two integers". However, the mainstream compilers like GCC and Clang implement this as the overflowed value, and some programmers also use this feature to do some tricky things. right?Įxactly, it is undefined behavior in the C++ standard. If there is undefined behavior then the value should be undefined and nothing else. As the developers may overflow an integer on purpose. Besides, the return value should be the exact value computed from the two integers, even unknown, rather than undefined.
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