[PATCH v3 1/4] KVM: arm64: vgic-its: Add a data length check in vgic_its_save_*

[Jing Zhang]

On Wed, Nov 6, 2024 at 4:03 AM Marc Zyngier <maz at kernel.org> wrote:
>
> On Wed, 06 Nov 2024 08:30:32 +0000,
> Jing Zhang <jingzhangos at google.com> wrote:
> >
> > From: Kunkun Jiang <jiangkunkun at huawei.com>
> >
> > In all the vgic_its_save_*() functinos, they do not check whether
> > the data length is 8 bytes before calling vgic_write_guest_lock.
> > This patch adds the check. To prevent the kernel from being blown up
> > when the fault occurs, KVM_BUG_ON() is used. And the other BUG_ON()s
> > are replaced together.
> >
> > Signed-off-by: Kunkun Jiang <jiangkunkun at huawei.com>
> > Signed-off-by: Jing Zhang <jingzhangos at google.com>
> > ---
> >  arch/arm64/kvm/vgic/vgic-its.c | 21 +++++++++++++++++++--
> >  1 file changed, 19 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c
> > index ba945ba78cc7..2381bc5ce544 100644
> > --- a/arch/arm64/kvm/vgic/vgic-its.c
> > +++ b/arch/arm64/kvm/vgic/vgic-its.c
> > @@ -2095,6 +2095,10 @@ static int vgic_its_save_ite(struct vgic_its *its, struct its_device *dev,
> >              ((u64)ite->irq->intid << KVM_ITS_ITE_PINTID_SHIFT) |
> >               ite->collection->collection_id;
> >       val = cpu_to_le64(val);
> > +
> > +     if (KVM_BUG_ON(ite_esz != sizeof(val), kvm))
> > +             return -EINVAL;
> > +
> >       return vgic_write_guest_lock(kvm, gpa, &val, ite_esz);
> >  }
> >
> > @@ -2250,6 +2254,10 @@ static int vgic_its_save_dte(struct vgic_its *its, struct its_device *dev,
> >              (itt_addr_field << KVM_ITS_DTE_ITTADDR_SHIFT) |
> >               (dev->num_eventid_bits - 1));
> >       val = cpu_to_le64(val);
> > +
> > +     if (KVM_BUG_ON(dte_esz != sizeof(val), kvm))
> > +             return -EINVAL;
> > +
> >       return vgic_write_guest_lock(kvm, ptr, &val, dte_esz);
> >  }
> >
> > @@ -2431,12 +2439,17 @@ static int vgic_its_save_cte(struct vgic_its *its,
> >                            struct its_collection *collection,
> >                            gpa_t gpa, int esz)
> >  {
> > +     struct kvm *kvm = its->dev->kvm;
>
> nit: just use its->dev->kvm consistently, as this is what we are
> already doing in this function.

Sure. Will do.
>
>         M.
>
> --
> Without deviation from the norm, progress is not possible.