ACK: [SRU][F:linux-bluefield][PATCH] net/sched: act_ct: fix ref leak when switching zones

[Tim Gardner]

On 6/16/22 16:50, Bodong Wang wrote:
> From: Marcelo Ricardo Leitner <marcelo.leitner at gmail.com>
> 
> BugLink: https://launchpad.net/bugs/1979009
> 
> When switching zones or network namespaces without doing a ct clear in
> between, it is now leaking a reference to the old ct entry. That's
> because tcf_ct_skb_nfct_cached() returns false and
> tcf_ct_flow_table_lookup() may simply overwrite it.
> 
> The fix is to, as the ct entry is not reusable, free it already at
> tcf_ct_skb_nfct_cached().
> 
> Reported-by: Florian Westphal <fw at strlen.de>
> Fixes: 2f131de361f6 ("net/sched: act_ct: Fix flow table lookup after ct clear or switching zones")
> Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner at gmail.com>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> Signed-off-by: Paul Blakey <paulb at nvidia.com>
> (backported from commit bcb74e132a76ce0502bb33d5b65533a4ed72d159)
> [paul: use ct_put rather than conntrack_put]
> Signed-off-by: Bodong Wang <bodong at nvidia.com>
> ---
>   net/sched/act_ct.c | 15 +++++++++------
>   1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c
> index ed310be..0f44608 100644
> --- a/net/sched/act_ct.c
> +++ b/net/sched/act_ct.c
> @@ -598,22 +598,25 @@ static bool tcf_ct_skb_nfct_cached(struct net *net, struct sk_buff *skb,
>   	if (!ct)
>   		return false;
>   	if (!net_eq(net, read_pnet(&ct->ct_net)))
> -		return false;
> +		goto drop_ct;
>   	if (nf_ct_zone(ct)->id != zone_id)
> -		return false;
> +		goto drop_ct;
>   
>   	/* Force conntrack entry direction. */
>   	if (force && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) {
>   		if (nf_ct_is_confirmed(ct))
>   			nf_ct_kill(ct);
>   
> -		nf_conntrack_put(&ct->ct_general);
> -		nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
> -
> -		return false;
> +		goto drop_ct;
>   	}
>   
>   	return true;
> +
> +drop_ct:
> +	nf_ct_put(ct);
> +	nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
> +
> +	return false;
>   }
>   
>   /* Trim the skb to the length specified by the IP/IPv6 header,
Acked-by: Tim Gardner <tim.gardner at canonical.com>

-- 
-----------
Tim Gardner
Canonical, Inc