Re: general protection fault in show_timer

[Eric Biggers]

On Thu, Dec 14, 2017 at 04:34:12PM +0100, Thomas Gleixner wrote:
> On Thu, 14 Dec 2017, Dmitry Vyukov wrote:
> > On Thu, Dec 14, 2017 at 3:26 PM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> > > On Tue, 12 Dec 2017, Greg KH wrote:
> > >> Did this ever go anywhere?  I don't see it in Linus's tree yet...
> > >
> > > I learned yesterday that syzboz is understuffed and cannot test patches, so
> > > I need to find a minute to run the reproducer myself and verify that the
> > > patch is correct.
> > 
> > Hi Thomas,
> > 
> > Why do you say so? Have you tried to ask it to test?
> > https://github.com/google/syzkaller/blob/master/docs/syzbot.md#communication-with-syzbot
> > What happened?
> 
> Eric explained that to me yesterday and I did not try yet. 
> 

Your patch definitely fixes the bug (I tested the C reproducers, you just need
to build a kernel with CONFIG_CHECKPOINT_RESTORE=y and CONFIG_POSIX_TIMERS=y,
then run them).  The real question is whether the check being introduced is too
strict -- are there users passing in other values for ->sigev_notify that would
be broken?  That I can't really answer.

Eric