Re: [PATCH v2] drm/amdkfd: Fix potential NULL pointer dereferences

[Gustavo A. R. Silva]

Quoting Oded Gabbay <oded.gabbay@xxxxxxxxx>:

> On Thu, Jan 11, 2018 at 1:15 AM, Gustavo A. R. Silva
> <garsilva@xxxxxxxxxxxxxx> wrote:
> > In case kfd_get_process_device_data returns null, there are some
> > null pointer dereferences in functions kfd_bind_processes_to_device
> > and kfd_unbind_processes_from_device.
> >
> > Fix this by printing a WARN_ON for PDDs that aren't found and skip
> > them with continue statements.
> >
> > Addresses-Coverity-ID: 1463794 ("Dereference null return value")
> > Addresses-Coverity-ID: 1463772 ("Dereference null return value")
> > Suggested-by: Felix Kuehling <felix.kuehling@xxxxxxx>
> > Signed-off-by: Gustavo A. R. Silva <garsilva@xxxxxxxxxxxxxx>
> > ---
> > Changes in v2:
> >  Print a WARN_ON and skip PDDs that aren't found instead of returning
> >  an error.
> >
> >  drivers/gpu/drm/amd/amdkfd/kfd_process.c | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c  
> > b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> > index a22fb071..4ff5f0f 100644
> > --- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> > +++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c
> > @@ -461,7 +461,8 @@ int kfd_bind_processes_to_device(struct kfd_dev *dev)
> >         hash_for_each_rcu(kfd_processes_table, temp, p, kfd_processes) {
> >                 mutex_lock(&p->mutex);
> >                 pdd = kfd_get_process_device_data(dev, p);
> > -               if (pdd->bound != PDD_BOUND_SUSPENDED) {
> > +
> > +               if (WARN_ON(!pdd) || pdd->bound != PDD_BOUND_SUSPENDED) {
> >                         mutex_unlock(&p->mutex);
> >                         continue;
> >                 }
> > @@ -501,6 +502,11 @@ void kfd_unbind_processes_from_device(struct  
> > kfd_dev *dev)
> >                 mutex_lock(&p->mutex);
> >                 pdd = kfd_get_process_device_data(dev, p);
> >
> > +               if (WARN_ON(!pdd)) {
> > +                       mutex_unlock(&p->mutex);
> > +                       continue;
> > +               }
> > +
> >                 if (pdd->bound == PDD_BOUND)
> >                         pdd->bound = PDD_BOUND_SUSPENDED;
> >                 mutex_unlock(&p->mutex);
> > --
> > 2.7.4
> This patch is:
> Reviewed-by: Oded Gabbay <oded.gabbay@xxxxxxxxx>

Thank you, Oded.
--
Gustavo