nvmet-rdma: Fix possible NULL deref when handling rdma cm events

When we initiate queue teardown sequence we call rdma_destroy_qp
which clears cm_id->qp, afterwards we call rdma_destroy_id, but
we might see a rdma_cm event in between with a cleared cm_id->qp
so watch out for that and silently ignore the event because this
means that the queue teardown sequence is in progress.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>

1 files changed, 7 insertions, 1 deletions

diff --git a/drivers/nvme/target/rdma.c b/drivers/nvme/target/rdma.c
index f8d23999e0f2..cf60759cc169 100644
--- a/drivers/nvme/target/rdma.c
+++ b/drivers/nvme/target/rdma.c
@@ -1352,7 +1352,13 @@ static int nvmet_rdma_cm_handler(struct rdma_cm_id *cm_id,
         case RDMA_CM_EVENT_ADDR_CHANGE:
         case RDMA_CM_EVENT_DISCONNECTED:
         case RDMA_CM_EVENT_TIMEWAIT_EXIT:
-                nvmet_rdma_queue_disconnect(queue);
+                /*
+                 * We might end up here when we already freed the qp
+                 * which means queue release sequence is in progress,
+                 * so don't get in the way...
+                 */
+                if (queue)
+                        nvmet_rdma_queue_disconnect(queue);
                 break;
         case RDMA_CM_EVENT_DEVICE_REMOVAL:
                 ret = nvmet_rdma_device_removal(cm_id, queue);