On Mon, Jul 15, 2024 at 09:19:49AM +0200, Martin Uecker wrote:
> The instrumentation is guarded by a new instrumentation flag -fvla-bounds,
> but runtime overhead should generally be very low as most checks are
> removed by the optimizer, e.g.
>
> void foo(int x, char (*buf)[x])
> {
> bar(x, buf);
> }
>
> does not have any overhead with -O1 (we also might want to filter out
> some obvious cases already in the FE). So I think this flag could be
> a good addition to -fhardened after some testing. Maybe it could even
> be activated by default.
Just to clarify, but does any of this change the behavior of
__builtin_object_size() or __builtin_dynamic_object_size() within
functions that take array arguments?
i.e. does this work now?
void foo(int array[10])
{
global = __builtin_object_size(array, 1);
}
(Currently "global" will be set to SIZE_MAX, rather than 40.)
--
Kees Cook
