RDMA/siw: Fix QP destroy to wait for all references dropped.

Delay QP destroy completion until all siw references to QP are
dropped. The calling RDMA core will free QP structure after
successful return from siw_qp_destroy() call, so siw must not
hold any remaining reference to the QP upon return.
A use-after-free was encountered in xfstest generic/460, while
testing NFSoRDMA. Here, after a TCP connection drop by peer,
the triggered siw_cm_work_handler got delayed until after
QP destroy call, referencing a QP which has already freed.

Fixes: 303ae1cdfdf7 ("rdma/siw: application interface")
Reported-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Bernard Metzler <bmt@zurich.ibm.com>
Link: https://lore.kernel.org/r/20220920082503.224189-1-bmt@zurich.ibm.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>

diff --git a/drivers/infiniband/sw/siw/siw.h b/drivers/infiniband/sw/siw/siw.h
index df03d84c6868ace3d5fe68c47e62cdd33e8b44d2..2f3a9cda3850f61c4b7c0d134c28a995714333c6 100644 (file)
--- a/drivers/infiniband/sw/siw/siw.h
+++ b/drivers/infiniband/sw/siw/siw.h
@@ -418,6 +418,7 @@ struct siw_qp {
        struct ib_qp base_qp;
        struct siw_device *sdev;
        struct kref ref;
+       struct completion qp_free;
        struct list_head devq;
        int tx_cpu;
        struct siw_qp_attrs attrs;

diff --git a/drivers/infiniband/sw/siw/siw_qp.c b/drivers/infiniband/sw/siw/siw_qp.c
index 7e01f2438afc5ed759182cac9a18514b92a7b850..e6f634971228e4993f26ac17a19fb41d8a588ed5 100644 (file)
--- a/drivers/infiniband/sw/siw/siw_qp.c
+++ b/drivers/infiniband/sw/siw/siw_qp.c
@@ -1342,6 +1342,6 @@ void siw_free_qp(struct kref *ref)
        vfree(qp->orq);
 
        siw_put_tx_cpu(qp->tx_cpu);
-
+       complete(&qp->qp_free);
        atomic_dec(&sdev->num_qp);
 }

diff --git a/drivers/infiniband/sw/siw/siw_verbs.c b/drivers/infiniband/sw/siw/siw_verbs.c
index 8dedae7ae79e681558712aefab90928df2670e58..3e814cfb298cf8342734fa6917eca138b2ee38b4 100644 (file)
--- a/drivers/infiniband/sw/siw/siw_verbs.c
+++ b/drivers/infiniband/sw/siw/siw_verbs.c
@@ -480,6 +480,8 @@ int siw_create_qp(struct ib_qp *ibqp, struct ib_qp_init_attr *attrs,
        list_add_tail(&qp->devq, &sdev->qp_list);
        spin_unlock_irqrestore(&sdev->lock, flags);
 
+       init_completion(&qp->qp_free);
+
        return 0;
 
 err_out_xa:
@@ -624,6 +626,7 @@ int siw_destroy_qp(struct ib_qp *base_qp, struct ib_udata *udata)
        qp->scq = qp->rcq = NULL;
 
        siw_qp_put(qp);
+       wait_for_completion(&qp->qp_free);
 
        return 0;
 }