RDMA/irdma: Prevent QP use after free

There is a window where the poll cq may use a QP that has been freed.
This can happen if a CQE is polled before irdma_clean_cqes() can clear the
CQE's related to the QP and the destroy QP races to free the QP memory.
then the QP structures are used in irdma_poll_cq.  Fix this by moving the
clearing of CQE's before the reference is removed and the QP is destroyed.

Fixes: b48c24c2d710 ("RDMA/irdma: Implement device supported verb APIs")
Link: https://lore.kernel.org/r/20230522155654.1309-3-shiraz.saleem@intel.com
Signed-off-by: Mustafa Ismail <mustafa.ismail@intel.com>
Signed-off-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/infiniband/hw/irdma/verbs.c b/drivers/infiniband/hw/irdma/verbs.c
index ab5cdf78278521123c92f8ff4482144797b765f6..68ce3cd400029d6d146e8b01941bec5a5920d3ef 100644 (file)
--- a/drivers/infiniband/hw/irdma/verbs.c
+++ b/drivers/infiniband/hw/irdma/verbs.c
@@ -522,11 +522,6 @@ static int irdma_destroy_qp(struct ib_qp *ibqp, struct ib_udata *udata)
        if (!iwqp->user_mode)
                cancel_delayed_work_sync(&iwqp->dwork_flush);
 
-       irdma_qp_rem_ref(&iwqp->ibqp);
-       wait_for_completion(&iwqp->free_qp);
-       irdma_free_lsmm_rsrc(iwqp);
-       irdma_cqp_qp_destroy_cmd(&iwdev->rf->sc_dev, &iwqp->sc_qp);
-
        if (!iwqp->user_mode) {
                if (iwqp->iwscq) {
                        irdma_clean_cqes(iwqp, iwqp->iwscq);
@@ -534,6 +529,12 @@ static int irdma_destroy_qp(struct ib_qp *ibqp, struct ib_udata *udata)
                                irdma_clean_cqes(iwqp, iwqp->iwrcq);
                }
        }
+
+       irdma_qp_rem_ref(&iwqp->ibqp);
+       wait_for_completion(&iwqp->free_qp);
+       irdma_free_lsmm_rsrc(iwqp);
+       irdma_cqp_qp_destroy_cmd(&iwdev->rf->sc_dev, &iwqp->sc_qp);
+
        irdma_remove_push_mmap_entries(iwqp);
        irdma_free_qp_rsrc(iwqp);