net/bnxt: fix a possible stack smashing

  We see a stack smashing as a result of defensive code missing. Once the
nb_pkts is less than RTE_BNXT_DESCS_PER_LOOP, it will be modified to
zero after doing a floor align, and we can not exit the following
receiving packets loop. And the buffers will be overwrite, then the
stack frame was ruined.

Fix the problem by adding defensive code, once the nb_pkts is zero, just
directly return with no packets.

Signed-off-by: yuanlinsi01 <yuanlinsi01@baidu.com>
Signed-off-by: rongdongsheng <rongdongsheng@baidu.com>
---
 drivers/net/bnxt/bnxt_rxtx_vec_sse.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)
  

+Lance Richardson

Thanks for the patch, could you please add the 'Fixes' tag as well ?



On Thu, Apr 30, 2020 at 5:35 PM yuanlinsi01 <yuanlinsi01@baidu.com> wrote:
>
> We see a stack smashing as a result of defensive code missing. Once the
> nb_pkts is less than RTE_BNXT_DESCS_PER_LOOP, it will be modified to
> zero after doing a floor align, and we can not exit the following
> receiving packets loop. And the buffers will be overwrite, then the
> stack frame was ruined.
>
> Fix the problem by adding defensive code, once the nb_pkts is zero, just
> directly return with no packets.
>
> Signed-off-by: yuanlinsi01 <yuanlinsi01@baidu.com>
> Signed-off-by: rongdongsheng <rongdongsheng@baidu.com>
> ---
>  drivers/net/bnxt/bnxt_rxtx_vec_sse.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/bnxt/bnxt_rxtx_vec_sse.c b/drivers/net/bnxt/bnxt_rxtx_vec_sse.c
> index d0e7910e7..c4adccdbc 100644
> --- a/drivers/net/bnxt/bnxt_rxtx_vec_sse.c
> +++ b/drivers/net/bnxt/bnxt_rxtx_vec_sse.c
> @@ -233,8 +233,13 @@ bnxt_recv_pkts_vec(void *rx_queue, struct rte_mbuf **rx_pkts,
>         /* Return no more than RTE_BNXT_MAX_RX_BURST per call. */
>         nb_pkts = RTE_MIN(nb_pkts, RTE_BNXT_MAX_RX_BURST);
>
> -       /* Make nb_pkts an integer multiple of RTE_BNXT_DESCS_PER_LOOP */
> +       /*
> +        * Make nb_pkts an integer multiple of RTE_BNXT_DESCS_PER_LOOP
> +        * nb_pkts < RTE_BNXT_DESCS_PER_LOOP, just return no packet
> +        */
>         nb_pkts = RTE_ALIGN_FLOOR(nb_pkts, RTE_BNXT_DESCS_PER_LOOP);
> +       if (!nb_pkts)
> +               return 0;
>
>         /* Handle RX burst request */
>         while (1) {
> --
> 2.11.0
>
  

Sure, I'll add it.


Thanks,

Yuan Linsi