[Octave-bug-tracker] [bug #59094] Possible integer overflow in __ode15__.cc

[Markus Mützel]

Update of bug #59094 (project octave):

                  Status:                    None => Patch Submitted        

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Follow-up Comment #2:

The attached patch adds functions that check whether multiplication of two
"similar" integers would overflow. These functions wrap around macros provided
by gnulib's `intprops` module.

It also adds the necessary check to `__ode15__.cc`.


The rules for integer multiplication between "dis-similar" integers and for
function dispatching in C++ might differ (I haven't checked).
But imho it would make code easier to understand (and possibly avoid
unintended behavior) if we explicitly casted to a common integer type before
such kinds of operation anyway. So I don't think it is necessary to add
functions that check integer overflow on operations between "dis-similar"
types (like "int type" times "unsigned long int type").


If needed, we could add similar check functions for other potentially critical
operations.
Checks are provided by gnulib for:
* addition
* subtraction
* negation
* multiplication
* division
* remainder
* left shift

See also:
https://www.gnu.org/software/gnulib/manual/html_node/Integer-Type-Overflow.html#Integer-Type-Overflow


Adding jwe to CC because he made the original proposition.


(file #49819)
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Additional Item Attachment:

File name: bug59094_ode15_integer_overflow.patch Size:9 KB
   
<https://file.savannah.gnu.org/file/bug59094_ode15_integer_overflow.patch?file_id=49819>



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