infiniband/qedr: Potential null ptr dereference of qp

idr_find() may fail and return a NULL pointer. The fix checks the return
value of the function and returns an error in case of NULL.
Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Acked-by: Michal Kalderon <michal.kalderon@marvell.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/qedr/qedr_iw_cm.c

@@ -492,6 +492,8 @@ int qedr_iw_connect(struct iw_cm_id *cm_id, struct iw_cm_conn_param *conn_param)
 	int i;
 
 	qp = idr_find(&dev->qpidr.idr, conn_param->qpn);
+	if (unlikely(!qp))
+		return -EINVAL;
 
 	laddr = (struct sockaddr_in *)&cm_id->m_local_addr;
 	raddr = (struct sockaddr_in *)&cm_id->m_remote_addr;