Re: [PATCH net 2/6] net: mscc: ocelot: avoid use after free with deleted tc-trap rules

[Vladimir Oltean <vladimir.oltean@nxp.com>]

On Tue, May 03, 2022 at 02:57:24PM +0300, Vladimir Oltean wrote:
> The error path of ocelot_flower_parse() removes a VCAP filter from
> ocelot->traps, but the main deletion path - ocelot_vcap_filter_del() -
> does not.
> 
> So functions such as felix_update_trapping_destinations() can still
> access the freed VCAP filter via ocelot->traps.
> 
> Fix this bug by removing the filter from ocelot->traps when it gets
> deleted.
> 
> Fixes: e42bd4ed09aa ("net: mscc: ocelot: keep traps in a list")
> Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
> ---
>  drivers/net/ethernet/mscc/ocelot_vcap.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/ethernet/mscc/ocelot_vcap.c b/drivers/net/ethernet/mscc/ocelot_vcap.c
> index 1e74bdb215ec..571d43e59f63 100644
> --- a/drivers/net/ethernet/mscc/ocelot_vcap.c
> +++ b/drivers/net/ethernet/mscc/ocelot_vcap.c
> @@ -1232,6 +1232,8 @@ static void ocelot_vcap_block_remove_filter(struct ocelot *ocelot,
>  		if (ocelot_vcap_filter_equal(filter, tmp)) {
>  			ocelot_vcap_filter_del_aux_resources(ocelot, tmp);
>  			list_del(&tmp->list);
> +			if (!list_empty(&tmp->trap_list))
> +				list_del(&tmp->trap_list);
>  			kfree(tmp);
>  		}
>  	}
> -- 
> 2.25.1
>

This change introduces other breakage, please drop this patch set and
allow me to come up with a different solution.