Re: [dpdk-dev] [PATCH v6 1/2] ethdev: fix data room size verification in Rx queue setup

[Slava Ovsiienko <viacheslavo@mellanox.com>]

Acked-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>

> -----Original Message-----
> From: dev <dev-bounces@dpdk.org> On Behalf Of Wei Hu (Xavier)
> Sent: Monday, July 6, 2020 10:07
> To: dev@dpdk.org
> Cc: xavier.huwei@huawei.com
> Subject: [dpdk-dev] [PATCH v6 1/2] ethdev: fix data room size verification in
> Rx queue setup
> 
> In the rte_eth_rx_queue_setup API function, the local variable named
> mbp_buf_size, which is the data room size of the input parameter mp, is
> checked to guarantee that each memory chunck used for net device in the
> mbuf is bigger than the min_rx_bufsize. But if mbp_buf_size is less than
> RTE_PKTMBUF_HEADROOM, the value of the following  statement will be a
> large number since the mbp_buf_size is a unsigned value.
>     mbp_buf_size - RTE_PKTMBUF_HEADROOM
> As a result, it will cause a segment fault in this situation.
> 
> This patch fixes it by modify the check condition to guarantee that the local
> varibale named mbp_buf_size is bigger than RTE_PKTMBUF_HEADROOM.
> 
> Fixes: af75078fece3 ("first public release")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Chengchang Tang <tangchengchang@huawei.com>
> Signed-off-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>
> Reviewed-by: Andrew Rybchenko <arybchenko@solarflare.com>
> Acked-by: Sachin Saxena <sachin.saxena@oss.nxp.com>
> ---
> v2 -> v6: No change.
> v1 -> v2: Simplify the check condition of mbp_buf_size according to
> 	  Andrew Rybchenko's comment.
> ---
>  lib/librte_ethdev/rte_ethdev.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
> index d06b7f9..50c3f18 100644
> --- a/lib/librte_ethdev/rte_ethdev.c
> +++ b/lib/librte_ethdev/rte_ethdev.c
> @@ -1820,7 +1820,7 @@ rte_eth_rx_queue_setup(uint16_t port_id,
> uint16_t rx_queue_id,
>  	}
>  	mbp_buf_size = rte_pktmbuf_data_room_size(mp);
> 
> -	if ((mbp_buf_size - RTE_PKTMBUF_HEADROOM) <
> dev_info.min_rx_bufsize) {
> +	if (mbp_buf_size < dev_info.min_rx_bufsize +
> RTE_PKTMBUF_HEADROOM) {
>  		RTE_ETHDEV_LOG(ERR,
>  			"%s mbuf_data_room_size %d < %d
> (RTE_PKTMBUF_HEADROOM=%d + min_rx_bufsize(dev)=%d)\n",
>  			mp->name, (int)mbp_buf_size,
> --
> 2.7.4