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Re: [RFC] kernel/panic: place an upper limit on number of oopses

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On Wed, Jan 13, 2016 at 10:34:39AM +1100, Daniel Axtens wrote:
> Jann Horn <jann@thejh.net> writes:
> > +	 * limit is reached, just panic.
> > +	 * The constant used as limit should be low enough to
> > +	 * mitigate this kind of exploitation attempt, but high
> > +	 * enough to avoid unnecessary panics.
> > +	 */
> > +	if (atomic_inc_return(&oops_counter) >= 0x100000 &&
> > +			panic_on_oops == 0) {
> Do you need to check panic_on_oops? If it was 1 you'd already have
> paniced, right?
[...]
> > +		pr_emerg("oopsed too often, setting panic_on_oops=1\n");
> > +		panic_on_oops = 1;
> Would it be easier to just panic here, rather than wait for another oops?

Ah, yes. So the code would be just this, apart from the definition of
oops_counter:

        if (atomic_inc_return(&oops_counter) >= 0x100000)
                panic("oopsed too often\n");

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Thread

[RFC] kernel/panic: place an upper limit on number of oopses Jann Horn <jann@thejh.net> - 2016-01-12 20:30 +0100
  Re: [RFC] kernel/panic: place an upper limit on number of oopses Daniel Axtens <dja@axtens.net> - 2016-01-13 00:40 +0100
    Re: [RFC] kernel/panic: place an upper limit on number of oopses Jann Horn <jann@thejh.net> - 2016-01-13 01:00 +0100
    Re: [RFC] kernel/panic: place an upper limit on number of oopses Solar Designer <solar@openwall.com> - 2016-01-13 01:30 +0100
      Re: [RFC] kernel/panic: place an upper limit on number of oopses Daniel Axtens <dja@axtens.net> - 2016-01-13 01:40 +0100
      Re: [RFC] kernel/panic: place an upper limit on number of oopses Jann Horn <jann@thejh.net> - 2016-01-13 19:10 +0100

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