Re: [PATCH] Staging: drivers/gpu/drm/amd/amdgpu: Fix null pointer deference in amdkfd_fence_get_timeline_name

[Christian König <christian.koenig@xxxxxxx>]

Am 20.09.24 um 18:31 schrieb Dipendra Khadka:
> On Fri, 20 Sept 2024 at 16:01, Christian König <christian.koenig@xxxxxxx> wrote:
> > Am 20.09.24 um 11:09 schrieb Dipendra Khadka:
> > > '''
> > > drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c:108:9: error: Null pointer dereference: fence [nullPointer]
> > >    return fence->timeline_name;
> > >           ^
> > > '''
> > >
> > > The method to_amdgpu_amdkfd_fence can return NULL incase of empty f
> > > or f->ops != &amdkfd_fence_ops.Hence, check has been added .
> > > If fence is null , then null is returned.
> > Well NAK, completely nonsense. Calling the function with a NULL fence is
> > illegal.
> Thanks for enlightening me .

Well sorry to be so direct, but what the heck did you tried to do here?

I mean that is broken on so many different levels that I can't 
understand why somebody is suggesting something like that.

Regards,
Christian.

> > Regards,
> > Christian.
> >
> > > Signed-off-by: Dipendra Khadka <kdipendra88@xxxxxxxxx>
> > > ---
> > >    drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c | 3 +++
> > >    1 file changed, 3 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
> > > index 1ef758ac5076..2313babcc944 100644
> > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
> > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c
> > > @@ -105,6 +105,9 @@ static const char *amdkfd_fence_get_timeline_name(struct dma_fence *f)
> > >    {
> > >        struct amdgpu_amdkfd_fence *fence = to_amdgpu_amdkfd_fence(f);
> > >
> > > +     if (!fence)
> > > +             return NULL;
> > > +
> > >        return fence->timeline_name;
> > >    }
> Regards,
> Dipendra Khadka