On Tue, Apr 20, 2021 at 09:39:50AM -0300, Jason Gunthorpe wrote:
> On Sun, Apr 18, 2021 at 04:37:35PM +0300, Leon Romanovsky wrote:
> > From: Shay Drory <shayd@xxxxxxxxxx>
> >
> > Currently, in case of QP, the following use-after-free is possible:
> >
> > cpu0 cpu1
> > ---- ----
> > res_get_common_dumpit()
> > rdma_restrack_get()
> > fill_res_qp_entry()
> > ib_destroy_qp_user()
> > rdma_restrack_del()
> > qp->device->ops.destroy_qp()
> > ib_query_qp()
> > qp->device->ops.query_qp()
> > --> use-after-free-qp
> >
> > This is because rdma_restrack_del(), in case of QP, isn't waiting until
> > all users are gone.
> >
> > Fix it by making rdma_restrack_del() wait until all users are gone for
> > QPs as well.
> >
> > Fixes: 13ef5539def7 ("RDMA/restrack: Count references to the verbs objects")
> > Signed-off-by: Shay Drory <shayd@xxxxxxxxxx>
> > Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxx>
> > ---
> > drivers/infiniband/core/restrack.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/infiniband/core/restrack.c b/drivers/infiniband/core/restrack.c
> > index ffabaf327242..def0c5b0efe9 100644
> > --- a/drivers/infiniband/core/restrack.c
> > +++ b/drivers/infiniband/core/restrack.c
> > @@ -340,7 +340,7 @@ void rdma_restrack_del(struct rdma_restrack_entry *res)
> > rt = &dev->res[res->type];
> >
> > old = xa_erase(&rt->xa, res->id);
> > - if (res->type == RDMA_RESTRACK_MR || res->type == RDMA_RESTRACK_QP)
> > + if (res->type == RDMA_RESTRACK_MR)
> > return;
>
> Why is MR skipping this?
I don't remember the justification for RDMA_RESTRACK_MR || RDMA_RESTRACK_QP check.
My guess that it is related to the allocation flow (both are not converted) and
have internal objects to the drivers.
>
>
> It also calls into the driver under its dumpit, at the very least this
> needs a comment.
>
> Jason
