On Wed, Nov 10, 2010 at 02:56:20PM -0500, Henrik Rydberg wrote:
> >>> @@ -977,7 +975,11 @@ static ssize_t applesmc_key_at_index_show
>
> >>> static ssize_t applesmc_key_at_index_store(struct device *dev,
> >>> struct device_attribute *attr, const char *sysfsbuf, size_t count)
> >>> {
> >>> - key_at_index = simple_strtoul(sysfsbuf, NULL, 10);
> >>> + unsigned long newkey;
> >>> +
> >>> + if (strict_strtoul(sysfsbuf, 10, &newkey) < 0)
> >>> + return -EINVAL;
> >>> + key_at_index = newkey;
> >>
> >>
> >> Crash alert - key_at_index is not range checked, and the remake uses this value
> >> as an array index...
> >>
> > Good that I made this change ;). I'll add the check and re-send.
>
>
> Indeed! The downside of remakes... sorry about that. :-)
>
Happens.
> I guess the change should go into patch 4 already? There is also the option to
> put the bounds check in applesmc_get_entry_by_index, but I like the simplicity
> of "|| newkey >= smcreg.key_count".
>
I don't like the idea of putting the check into applesmc_get_entry_by_index().
Let me see if I can merge it into patch #4. If not, I'll keep it in my patch
for simplicity.
> > This points to another problem, though. You allocate key_count entries,
> > ie cache[0]..cache[key_count-1]. Yet, the key searches are from 0..key_count,
> > ie span key_count+1 entries. Is that another problem ?
>
> >
>
> > Seems to me you would either have to allocate key_count+1 entries, or terminate
> > the search at key_count - 1. Not sure which one would be correct. Let me know,
> > and I'll update the affected patch(es).
>
>
> If you are referring to the lower and upper bound functions, those use the
> one-past-the-last-element convention, so it is actually still 0..key_count - 1.
> I stayed very close to the stl reference implementation, which relies on the
> fact that when begin != end, (begin + (end - begin) / 2) < end.
>
Ok, you are right - I was concerned about applesmc_get_upper_bound() returning
smcreg.key_count, but that is ok, since that value is never used to actually
retrieve a key.
Thanks,
Guenter
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