Re: [dpdk-dev] [PATCH v4 1/2] ethdev: fix data room size verification in Rx queue setup

["Sachin Saxena (OSS)" <sachin.saxena@oss.nxp.com>]

Acked-by: Sachin Saxena<sachin.saxena@oss.nxp.com>


On 22-Jun-20 1:38 PM, Wei Hu (Xavier) wrote:
> 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>
> ---
> v3 -> v4: No change.
> v2 -> v3: 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 8e10a6f..b0b0474 100644
> --- a/lib/librte_ethdev/rte_ethdev.c
> +++ b/lib/librte_ethdev/rte_ethdev.c
> @@ -1822,7 +1822,7 @@ 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,