Re: [patch 1/2] Validate itimer timeval from userspace

[Jesper Juhl]

On 3/18/06, Andrew Morton <akpm@xxxxxxxx> wrote:
> "Jesper Juhl" <jesper.juhl@xxxxxxxxx> wrote:
> >
> > > It would be strange to set an alarm for 0xffffffff seconds in the future
> >  > but yeah, unless we can point at a reason why nobody could have ever been
> >  > doing that, we should turn this into permanent, documented behaviour of
> >  > Linux 2.6 and earlier, I'm afraid.
> >  >
> >
> >  How about 0xffffffff seconds into the future being the same as 136
> >  years (unless I botched the math)... That means that if any Linux
> >  application ever did that it's still waiting for the alarm and will be
> >  for at least another century...
> >  I'd say that makes it pretty certain that noone are doing or have been
> >  doing that without spotting the problem somehow - apps with such a bug
> >  are unlikely to be in production and actually working correctly.
>
> We just don't know.  People do all sorts of things.
>
> How about this?
>
>         $ cat /etc/my-expensive-app.conf
>         #
>         # Interval polling timer.  Set this to -1 to disable
>         #
>         interval_polling_timer=-1
>
> We just don't know.
>
True, someone might be doing something like that, but consider this as well;

an app promts the user to enter a value and passes it on, expecting to
get EINVAL back if the value is wrong and has code in place to handle
that (like, say, prompt the user for a different value).

That app is not buggy, but it will not work correctly because *we* are buggy.

IMO we should cater to the correctly written app and prevent it from
breaking unexpectedly rather than continue to keep the buggy one
working.

--
Jesper Juhl <jesper.juhl@xxxxxxxxx>
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