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

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Date:   Wed, 4 May 2022 21:10:21 +0000
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vladimir Oltean <olteanv@...il.com>,
        Claudiu Manoil <claudiu.manoil@....com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        "UNGLinuxDriver@...rochip.com" <UNGLinuxDriver@...rochip.com>,
        Xiaoliang Yang <xiaoliang.yang_1@....com>,
        Colin Foster <colin.foster@...advantage.com>
Subject: Re: [PATCH net 2/6] net: mscc: ocelot: avoid use after free with
 deleted tc-trap rules

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@....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.