Re: [PATCH V2 3/3] perf/x86/intel/uncore: Validate MMIO address before accessing

[Liang, Kan]

On 5/28/2020 9:30 AM, Andi Kleen wrote:
> On Thu, May 28, 2020 at 06:15:27AM -0700, kan.liang@xxxxxxxxxxxxxxx wrote:
> > From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
> >
> > An oops will be triggered, if perf tries to access an invalid address
> > which exceeds the mapped area.
> >
> > Check the address before the actual access to MMIO sapce of an uncore
> > unit.
>
> Ah ok the range check is here
>
> > Suggested-by: David Laight <David.Laight@xxxxxxxxxx>
> > Signed-off-by: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
> > ---
> >   arch/x86/events/intel/uncore.c       |  3 +++
> >   arch/x86/events/intel/uncore.h       | 12 ++++++++++++
> >   arch/x86/events/intel/uncore_snbep.c |  6 ++++++
> >   3 files changed, 21 insertions(+)
> >
> > diff --git a/arch/x86/events/intel/uncore.c b/arch/x86/events/intel/uncore.c
> > index cf76d66..284f8e7 100644
> > --- a/arch/x86/events/intel/uncore.c
> > +++ b/arch/x86/events/intel/uncore.c
> > @@ -132,6 +132,9 @@ u64 uncore_mmio_read_counter(struct intel_uncore_box *box,
> >   	if (!box->io_addr)
> >   		return 0;
> >   
> > +	if (!is_valid_mmio_offset(box, event->hw.event_base))
> > +		return 0;
>
> Is this function used somewhere else? Otherwise it should be added
> together with its users.

Yes, it's generic function. Current MMIO uncore units invoke it to read 
counter.

Thanks,
Kan