IB/mlx4: Check iboe netdev pointer before dereferencing it

Unlike other parts of the mlx4_ib code, the function build_mlx_header()
doesn't check if the iboe netdev of the given port is valid before
dereferencing it, which can cause a crash if the ethernet interface
has already been taken down.

Fix this by checking for a valid netdev pointer before using it to get
the port MAC address.

Signed-off-by: Kleber Sacilotto de Souza <klebers@linux.vnet.ibm.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

diff --git a/drivers/infiniband/hw/mlx4/qp.c b/drivers/infiniband/hw/mlx4/qp.c
index a6d8ea060ea896ad4f7c7d9a8639a8be8f67fb4e..f585eddef4b7d5c7921575cebaa508eefde4f934 100644 (file)
--- a/drivers/infiniband/hw/mlx4/qp.c
+++ b/drivers/infiniband/hw/mlx4/qp.c
@@ -1407,6 +1407,7 @@ static int build_mlx_header(struct mlx4_ib_sqp *sqp, struct ib_send_wr *wr,
        struct mlx4_wqe_mlx_seg *mlx = wqe;
        struct mlx4_wqe_inline_seg *inl = wqe + sizeof *mlx;
        struct mlx4_ib_ah *ah = to_mah(wr->wr.ud.ah);
+       struct net_device *ndev;
        union ib_gid sgid;
        u16 pkey;
        int send_size;
@@ -1483,7 +1484,10 @@ static int build_mlx_header(struct mlx4_ib_sqp *sqp, struct ib_send_wr *wr,
 
                memcpy(sqp->ud_header.eth.dmac_h, ah->av.eth.mac, 6);
                /* FIXME: cache smac value? */
-               smac = to_mdev(sqp->qp.ibqp.device)->iboe.netdevs[sqp->qp.port - 1]->dev_addr;
+               ndev = to_mdev(sqp->qp.ibqp.device)->iboe.netdevs[sqp->qp.port - 1];
+               if (!ndev)
+                       return -ENODEV;
+               smac = ndev->dev_addr;
                memcpy(sqp->ud_header.eth.smac_h, smac, 6);
                if (!memcmp(sqp->ud_header.eth.smac_h, sqp->ud_header.eth.dmac_h, 6))
                        mlx->flags |= cpu_to_be32(MLX4_WQE_CTRL_FORCE_LOOPBACK);