Re: get_arg_page() && ptr_size accounting

[Oleg Nesterov]

On 09/10, Kees Cook wrote:
>
> On Mon, Sep 10, 2018 at 10:43 AM, Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
> >
> > with this patch
> >
> >         #define MAX_ARG_STRINGS 0x7FFFFFFF
> >
> > doesn't match the reality. perhaps something like below makes sense just
> > to make it clear, but this is cosmetic.
>
> Part of the discussion from back then was basically "we don't have
> hard-coded limits so programs need to check dynamically themselves".
>
> I'd prefer to leave it all well enough alone since I don't want to
> introduce regressions here in the face of the many many Stack Clash
> style weaknesses.

I simply can't understand... Perhaps you too misunderstood me, I only
tried to say that count() can stop earlier, it is pointless to continue
to count the arg/env strings after argc + envc > _STK_LIM / 4 * 3 / 2,
copy_strings() will fail anyway.

Oleg.