Re: [PATCH] infiniband: Fix a use after free in isert_connect_request

[Leon Romanovsky <leon@kernel.org>]

On Mon, Mar 22, 2021 at 06:53:55AM -0700, Lv Yunlong wrote:
> The device is got by isert_device_get() with refcount is 1,
> and is assigned to isert_conn by isert_conn->device = device.
> When isert_create_qp() failed, device will be freed with
> isert_device_put().
> 
> Later, the device is used in isert_free_login_buf(isert_conn)
> by the isert_conn->device->ib_device statement. My patch
> exchanges the callees order to free the device late.
> 
> Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
> ---
>  drivers/infiniband/ulp/isert/ib_isert.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

The fix needs to be change of isert_free_login_buf() from
isert_free_login_buf(isert_conn) to be isert_free_login_buf(isert_conn, cma_id->device)

Thanks

> 
> diff --git a/drivers/infiniband/ulp/isert/ib_isert.c b/drivers/infiniband/ulp/isert/ib_isert.c
> index 7305ed8976c2..d8a533e346b0 100644
> --- a/drivers/infiniband/ulp/isert/ib_isert.c
> +++ b/drivers/infiniband/ulp/isert/ib_isert.c
> @@ -473,10 +473,10 @@ isert_connect_request(struct rdma_cm_id *cma_id, struct rdma_cm_event *event)
>  
>  out_destroy_qp:
>  	isert_destroy_qp(isert_conn);
> -out_conn_dev:
> -	isert_device_put(device);
>  out_rsp_dma_map:
>  	isert_free_login_buf(isert_conn);
> +out_conn_dev:
> +	isert_device_put(device);
>  out:
>  	kfree(isert_conn);
>  	rdma_reject(cma_id, NULL, 0, IB_CM_REJ_CONSUMER_DEFINED);
> -- 
> 2.25.1
> 
>