Re: [PATCH for-rc] RDMA/qedr: Fix Null pointer dereference when running over iWARP without RDMA-CM

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On Mon, Jun 11, 2018 at 04:13:23PM +0000, Parav Pandit wrote:
> Hi Michal,
> 
> > From: linux-rdma-owner@xxxxxxxxxxxxxxx [mailto:linux-rdma-
> > owner@xxxxxxxxxxxxxxx] On Behalf Of Michal Kalderon
> > Sent: Monday, June 11, 2018 2:20 AM
> > To: michal.kalderon@xxxxxxxxxx; Jason Gunthorpe <jgg@xxxxxxxxxxxx>;
> > dledford@xxxxxxxxxx
> > Cc: linux-rdma@xxxxxxxxxxxxxxx; yuval.bason@xxxxxxxxxx; Michal Kalderon
> > <Michal.Kalderon@xxxxxxxxxx>; Ariel Elior <Ariel.Elior@xxxxxxxxxx>
> > Subject: [PATCH for-rc] RDMA/qedr: Fix Null pointer dereference when running
> > over iWARP without RDMA-CM
> > 
> > Some RoCE specific code in qedr_modify_qp was run over an iWARP device
> > when running perftest benchmarks without the -R option.
> > 
> > The commit 3e44e0ee0893 ("IB/providers: Avoid null netdev check for RoCE")
> > exposed this. Dropping the check for NULL pointer on ndev in qedr_modify_qp
> > lead to a null pointer dereference when running over iWARP. Before the code
> > would identify ndev as being NULL and return an error.
> Previously get_gid_info_from_table() with valid gid index would return success and was doing things conditionally if ndev was set.
> 
> > 
> > Fixes: 3e44e0ee0893 ("IB/providers: Avoid null netdev check for RoCE")
> > Signed-off-by: Ariel Elior <Ariel.Elior@xxxxxxxxxx>
> > Signed-off-by: Michal Kalderon <Michal.Kalderon@xxxxxxxxxx>
> >  drivers/infiniband/hw/qedr/verbs.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/drivers/infiniband/hw/qedr/verbs.c
> > b/drivers/infiniband/hw/qedr/verbs.c
> > index 3f9afc0..f86223a 100644
> > +++ b/drivers/infiniband/hw/qedr/verbs.c
> > @@ -1957,6 +1957,9 @@ int qedr_modify_qp(struct ib_qp *ibqp, struct
> > ib_qp_attr *attr,
> >  	}
> > 
> >  	if (attr_mask & (IB_QP_AV | IB_QP_PATH_MTU)) {
> > +		if (rdma_protocol_iwarp(&dev->ibdev, 1))
> > +			return -EINVAL;
> > +
> RB: parav@xxxxxxxxxxxx
> 
> A check like rdma_protocol_roce() similar to what you have already for stack check makes it more clear that this is for roce.
> That likely preserves old behavior, I think.
> 
> -       if (attr_mask & (IB_QP_AV | IB_QP_PATH_MTU)) {
> +       if (attr_mask & (IB_QP_AV | IB_QP_PATH_MTU) &&
> +           rdma_protocol_roce(&dev->ibdev, 1)) {
> 
> Many checks in this function are for RoCE such as IB_QP_RETRY_CNT, IB_QP_RNR_RETRY, IB_QP_RQ_PSN, 
> IB_QP_MIN_RNR_TIMER, IB_QP_SQ_PSN, IB_QP_QKEY, IB_QP_PKEY_INDEX.
> 
> So for for-next, (not for-rc),
> 1. You should refactor the function to split code for roce and iwarp so that right checks and settings are done for right transport.
> It makes code more clear.
> 
> 2. I would expect that ib_modify_qp_is_ok() should be extended for iWarp as well, so that when IB_QP_AV | IB_QP_PATH_MTU is set, provider driver doesn't have to do this check to return failure error code.
> 
> 3. ib_modify_qp_is_ok() already has input parameter to pass link_layer. It should be extended, to honor do right state specific mask checks for right link layer.

This comment will make more sense when Parav's next series is
posted..

But I think the iWarp team needs to get their heads together and
figure out how to create a struct ib_gid_attr for iWarp that includes
the proper netdev.

I seriously doubt iWarp will work fully properly re namespaces and
other difficult races without this..

If enough iWarp folks are coming the plumbers conference in November
it would make a good RDMA mini-conf topic.

Jason
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