[PATCH] net/xsc: fix use after free in some RXQ cleanup

[Renyong Wan]

Thanks David for catching this issue.
We'll address it in the 25.11 release.

On 2025/9/9 15:04, David Marchand wrote:
> Debian 12 gcc complains about a use after free in this cleanup section.
>
> [7/11] Compiling C object drivers/libtmp_rte_net_xsc.a.p/net_xsc_xsc_rx.c.o
> In function 'xsc_rss_qp_create',
>      inlined from 'xsc_rxq_rss_obj_new' at ../drivers/net/xsc/xsc_rx.c:565:8:
> ../drivers/net/xsc/xsc_rx.c:501:9: warning: pointer 'req' may be used after
> 	'free' [-Wuse-after-free]
>    501 |         free(req);
>        |         ^~~~~~~~~
> ../drivers/net/xsc/xsc_rx.c:501:9: note: call to 'free' here
>
> Indeed, req may be free'd twice, as an error in the cleanup loop may
> jump back to the set_qp_fail label.
>
> Instead, skip the erroneous rxq and don't touch errno since all the code
> jumping to set_qp_fail already sets it.
>
> Fixes: 3991c890fb4c ("net/xsc: optimize RSS queue creation")
>
> Signed-off-by: David Marchand <david.marchand at redhat.com>
> ---
>   drivers/net/xsc/xsc_rx.c | 6 ++----
>   1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/xsc/xsc_rx.c b/drivers/net/xsc/xsc_rx.c
> index 5f8003a1f6..5ff3f818c2 100644
> --- a/drivers/net/xsc/xsc_rx.c
> +++ b/drivers/net/xsc/xsc_rx.c
> @@ -502,10 +502,8 @@ xsc_rss_qp_create(struct xsc_ethdev_priv *priv, int port_id)
>   	for (i = 0; i < set_last_no; i++) {
>   		xsc_unset_qp_info(xdev, rqn_base + i);
>   		rxq_data = xsc_rxq_get(priv, i);
> -		if (rxq_data == NULL) {
> -			rte_errno = EINVAL;
> -			goto set_qp_fail;
> -		}
> +		if (rxq_data == NULL)
> +			continue;
>   		rte_memzone_free(rxq_data->rq_pas);
>   		rxq_data->rq_pas = NULL;
>   	}


-- 
Best regards,
Renyong Wan