Re: [PATCH] netfilter: nf_conntrack_bridge: Fix not free when error

[Pablo Neira Ayuso]

On Mon, Jul 26, 2021 at 11:57:02AM +0800, Yajun Deng wrote:
> It should be added kfree_skb_list() when err is not equal to zero
> in nf_br_ip_fragment().
> 
> Fixes: 3c171f496ef5 ("netfilter: bridge: add connection tracking system")
> Signed-off-by: Yajun Deng <yajun.deng@xxxxxxxxx>
> ---
>  net/bridge/netfilter/nf_conntrack_bridge.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/net/bridge/netfilter/nf_conntrack_bridge.c b/net/bridge/netfilter/nf_conntrack_bridge.c
> index 8d033a75a766..059f53903eda 100644
> --- a/net/bridge/netfilter/nf_conntrack_bridge.c
> +++ b/net/bridge/netfilter/nf_conntrack_bridge.c
> @@ -83,12 +83,16 @@ static int nf_br_ip_fragment(struct net *net, struct sock *sk,
>  
>  			skb->tstamp = tstamp;
>  			err = output(net, sk, data, skb);
> -			if (err || !iter.frag)
> -				break;
> -
> +			if (err) {
> +				kfree_skb_list(iter.frag);
> +				return err;
> +			}
> +
> +			if (!iter.frag)
> +				return 0;
> +
>  			skb = ip_fraglist_next(&iter);
>  		}
> -		return err;

Why removing this line above? It enters slow_path: on success.

This patch instead will keep this aligned with IPv6.

>  	}
>  slow_path:
>  	/* This is a linearized skbuff, the original geometry is lost for us.
> -- 
> 2.32.0
> 
diff --git a/net/bridge/netfilter/nf_conntrack_bridge.c b/net/bridge/netfilter/nf_conntrack_bridge.c
index 8d033a75a766..3cf5457919c6 100644
--- a/net/bridge/netfilter/nf_conntrack_bridge.c
+++ b/net/bridge/netfilter/nf_conntrack_bridge.c
@@ -88,6 +88,11 @@ static int nf_br_ip_fragment(struct net *net, struct sock *sk,
 
 			skb = ip_fraglist_next(&iter);
 		}
+
+		if (!err)
+			return 0;
+
+		kfree_skb_list(iter.frag_list);
 		return err;
 	}
 slow_path: