Re: panic: invalid bcd xxx

On Tue, 28 Feb 2017 17:16:02 -0600
Eric van Gyzen <vangyzen_at_FreeBSD.org> wrote:

> On 02/28/2017 16:57, Conrad Meyer wrote:
> > On Tue, Feb 28, 2017 at 2:31 PM, Eric van Gyzen
> > <vangyzen_at_freebsd.org> wrote:  
> >> Your system's real-time clock is returning garbage.  r312702 added
> >> some input validation a few weeks ago.  Previously, the kernel was
> >> reading beyond the end of an array and either complaining about
> >> the clock or setting it to the wrong time based on whatever was in
> >> the memory beyond the array.
> >>
> >> The added validation shouldn't be an assertion because it operates
> >> on data beyond the kernel's control.  Try this:
> >>
> >> --- sys/libkern.h       (revision 314424)
> >> +++ sys/libkern.h       (working copy)
> >> _at__at_ -57,8 +57,10 _at__at_
> >>  bcd2bin(int bcd)
> >>  {
> >>
> >> -       KASSERT(bcd >= 0 && bcd < LIBKERN_LEN_BCD2BIN,
> >> -           ("invalid bcd %d", bcd));
> >> +       if (bcd < 0 || bcd >= LIBKERN_LEN_BCD2BIN) {
> >> +               printf("invalid bcd %d\n", bcd);
> >> +               return (0);
> >> +       }
> >>         return (bcd2bin_data[bcd]);
> >>  }  
> >
> > I don't think removing this assertion and truncating to zero is the
> > right thing to do.  Adding an error return to this routine is a
> > little much, though.  I think probably the caller should perform
> > input validation between the broken device and this routine.  
> 
> Either of those would be a much better solution.  This was just a
> quick hack to get the memstick to boot.
> 

Thanks for your response.

I'm not in a hurry, so I can wait for a proper solution. Let me know if
I should test anything or can help in some other way.

-m


-- 
Michael Gmelin