Notify special task kill using wait* functions

[John Wood]

Hi,

On Sun, Apr 04, 2021 at 05:10:25PM -0400, Valdis Klētnieks wrote:
> On Sun, 04 Apr 2021 11:48:37 +0200, John Wood said:
>
> > that exec and the child crashes is mitigated. The only drawback here, as
> > point Andi, is that a supervisor respawns some process killed. To avoid
> > this situation he suggest to notify to usersapace via wait* that the
> > task has been killed by "brute". Then, this supervisor has the chance to
> > do what they need (respawn or not).
>
> And how does the kernel know that it's notifying a "real" supervisor process,
> and not a process started by the bad guy, who can receive the notification
> and decide to respawn?
>
Well, I think this is not possible to know. Anyway, I believe that the "bad
guy" not rely on the wait* notification to decide to respawn or not. He
will do the attack without waiting any notification.

Anyway thanks a lot for this new point of view.

Thanks,
John Wood