Re: [dpdk-stable] [dpdk-dev] [PATCH v5] ethdev: fix DCB set failure

[Andrew Rybchenko <arybchenko@solarflare.com>]

CC net/nfp maintainer

On 5/13/20 8:16 PM, Ting Xu wrote:
> When rte_eth_dev_rss_hash_conf_get() is called, if the variable
> rss_conf is not initialized, the pointer member variable rss_key
> may have a random address, which leads to an error in the following
> processing. This patch initialized the variable rss_conf to avoid
> this situation.
> 
> Fixes: 16321de09396 ("ethdev: allow to get RSS hash functions and key")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Ting Xu <ting.xu@intel.com>
> 
> ---
> v4->v5: modify commit log
> V3->v4: fix build failure
> v2->v3: move memset to rte_eth_dev_rss_hash_conf_get from testpmd
> v1->v2: modify commit log, move memset to else leg
> ---
>  lib/librte_ethdev/rte_ethdev.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
> index 8e10a6fc3..b20c6bb2d 100644
> --- a/lib/librte_ethdev/rte_ethdev.c
> +++ b/lib/librte_ethdev/rte_ethdev.c
> @@ -3552,6 +3552,7 @@ rte_eth_dev_rss_hash_conf_get(uint16_t port_id,
>  	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
>  	dev = &rte_eth_devices[port_id];
>  	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->rss_hash_conf_get, -ENOTSUP);
> +	memset(rss_conf, 0, sizeof(*rss_conf));
>  	return eth_err(port_id, (*dev->dev_ops->rss_hash_conf_get)(dev,
>  								   rss_conf));
>  }
> 

The patch breaks getting of RSS key since it resets rss_conf->rss_key to
NULL, but all drivers treat it as
a  pointer to buffer to copy RSS key to.
Almost all driver just skip RSS key copy if the pointer
is NULL.

I think it should be removed from next-net or improved
to reset rss_hf only since rss_key_len may be treated
as a size of rss_key buffer. The API is not clear at
the place.

It looks like net/nfp is the only driver which does
not check that that pointer is not NULL before coping
key to it.