On 2017.03.23 14:43:44 +0100, Frans Klaver wrote:
> On Thu, Mar 23, 2017 at 1:22 PM, Colin King <colin.king@xxxxxxxxxxxxx> wrote:
> > From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> >
> > info is being checked to see if it is a null pointer, however, vpgu is
> > dereferencing info before this check, leading to a potential null
> > pointer dereference. If info is null, then the error message being
> > printed by macro gvt_vgpu_err and this requires vpgu to exist. We can
> > use a null vpgu as the macro has a sanity check to see if vpgu is null,
> > so this is OK.
> >
> > Detected with CoverityScan, CID#1420672 ("Dereference nefore null check")
>
> s,nefore,before,
>
>
> >
> > Fixes: 695fbc08d80f ("drm/i915/gvt: replace the gvt_err with gvt_vgpu_err")
> > Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/gvt/kvmgt.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gvt/kvmgt.c b/drivers/gpu/drm/i915/gvt/kvmgt.c
> > index 1ea3eb270de8..f8619a772c44 100644
> > --- a/drivers/gpu/drm/i915/gvt/kvmgt.c
> > +++ b/drivers/gpu/drm/i915/gvt/kvmgt.c
> > @@ -1339,9 +1339,9 @@ static int kvmgt_guest_init(struct mdev_device *mdev)
> >
> > static bool kvmgt_guest_exit(struct kvmgt_guest_info *info)
> > {
> > - struct intel_vgpu *vgpu = info->vgpu;
> > -
> > if (!info) {
> > + struct intel_vgpu *vgpu = NULL;
> > +
> > gvt_vgpu_err("kvmgt_guest_info invalid\n");
> > return false;
> > }
>
> Does this mean the original gvt_err() macro is no longer there?
>
> And apparently gvt_vgpu_err is a macro that depends on the specifics
> of its environment? Yikes.
>
The null check is redundant there, we can just remove that block and extra
vgpu variable.
--
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