Re: [PATCH] timekeeping: Limit system time to prevent 32-bit time_t overflow

From	Thomas Gleixner <tglx@linutronix.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH] timekeeping: Limit system time to prevent 32-bit time_t overflow
Date	2015-10-09 11:50 +0200
Message-ID	<qhCtk-6Ne-31@gated-at.bofh.it> (permalink)
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On Thu, 8 Oct 2015, Miroslav Lichvar wrote:
> On Thu, Oct 08, 2015 at 10:52:05AM +0200, Arnd Bergmann wrote:
> > On Thursday 08 October 2015 08:23:44 Miroslav Lichvar wrote:
> > > The difference is that with the one-week step the kernel and userspace
> > > still agree on the current time and it is always valid from the kernel
> > > point of view, absolute timers can be set, etc.
> > 
> > Ok, I can see that as an improvement, but it still seems to give
> > a false sense of safety, and I feel we really should not have any code
> > rely on this behavior.
> 
> Applications are not allowed to rely on system time being sane?
> To me the current behavior looks like the kernel is throwing the
> applications off a cliff, while it's the only thing that can fly :).

As Arnd said, you are creating a wrong sense of safety. They fall off
the cliff with your changes as well. The fall is just different. Think
about timeouts, user space overflows of time_t etc.

We need to fix all of it, no matter what.

Thanks,

	tglx




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Thread

[PATCH] timekeeping: Limit system time to prevent 32-bit time_t overflow Miroslav Lichvar <mlichvar@redhat.com> - 2015-10-07 15:30 +0200
  Re: [PATCH] timekeeping: Limit system time to prevent 32-bit time_t overflow Arnd Bergmann <arnd@arndb.de> - 2015-10-07 15:50 +0200
    Re: [PATCH] timekeeping: Limit system time to prevent 32-bit time_t  overflow Miroslav Lichvar <mlichvar@redhat.com> - 2015-10-07 16:30 +0200
      Re: [PATCH] timekeeping: Limit system time to prevent 32-bit time_t overflow Arnd Bergmann <arnd@arndb.de> - 2015-10-07 17:20 +0200
        Re: [PATCH] timekeeping: Limit system time to prevent 32-bit time_t  overflow Miroslav Lichvar <mlichvar@redhat.com> - 2015-10-08 08:30 +0200
          Re: [PATCH] timekeeping: Limit system time to prevent 32-bit time_t overflow Arnd Bergmann <arnd@arndb.de> - 2015-10-08 11:00 +0200
            Re: [PATCH] timekeeping: Limit system time to prevent 32-bit time_t  overflow Miroslav Lichvar <mlichvar@redhat.com> - 2015-10-08 11:40 +0200
              Re: [PATCH] timekeeping: Limit system time to prevent 32-bit time_t  overflow Thomas Gleixner <tglx@linutronix.de> - 2015-10-09 11:50 +0200
                Re: [PATCH] timekeeping: Limit system time to prevent 32-bit time_t  overflow Thomas Gleixner <tglx@linutronix.de> - 2015-10-09 12:40 +0200
                Re: [PATCH] timekeeping: Limit system time to prevent 32-bit time_t  overflow Miroslav Lichvar <mlichvar@redhat.com> - 2015-10-09 12:50 +0200
                Re: [PATCH] timekeeping: Limit system time to prevent 32-bit time_t  overflow Miroslav Lichvar <mlichvar@redhat.com> - 2015-10-09 12:40 +0200

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