> On 10/20/2017 12:37 AM, Elena Reshetova wrote:
> > atomic_t variables are currently used to implement reference
> > counters with the following properties:
> > - counter is initialized to 1 using atomic_set()
> > - a resource is freed upon counter reaching zero
> > - once counter reaches zero, its further
> > increments aren't allowed
> > - counter schema uses basic atomic operations
> > (set, inc, inc_not_zero, dec_and_test, etc.)
> >
> > Such atomic variables should be converted to a newly provided
> > refcount_t type and API that prevents accidental counter overflows
> > and underflows. This is important since overflows and underflows
> > can lead to use-after-free situation and be exploitable.
> >
> > The variable cached_dev.count is used as pure reference counter.
> > Convert it to refcount_t and fix up the operations.
> >
> > Suggested-by: Kees Cook <keescook@xxxxxxxxxxxx>
> > Reviewed-by: David Windsor <dwindsor@xxxxxxxxx>
> > Reviewed-by: Hans Liljestrand <ishkamiel@xxxxxxxxx>
> > Signed-off-by: Elena Reshetova <elena.reshetova@xxxxxxxxx>
>
> Reviewed-by: Michael Lyle <mlyle@xxxxxxxx>
>
> Thanks for this-- I'm including it in my tree for possible inclusion in
> 4.15 (I've already sent my main chunk of changes upwards).
Thank you Mike! I am dropping then this patch from my list of maintained
conversions.
Best Regards,
Elena.
>
> Mike
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