linux-kernel - Re: [PATCH] netfilter: fix dangling pointer access of fake

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Message-ID: <20190422083339.ptkxqb66pombgy5g@salvia>
Date:   Mon, 22 Apr 2019 10:33:59 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     Rundong Ge <rdong.ge@...il.com>
Cc:     kadlec@...ckhole.kfki.hu, fw@...len.de, roopa@...ulusnetworks.com,
        davem@...emloft.net, netfilter-devel@...r.kernel.org,
        coreteam@...filter.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] netfilter: fix dangling pointer access of fake_rtable

On Tue, Apr 09, 2019 at 06:56:12AM +0000, Rundong Ge wrote:
[...]
> diff --git a/net/netfilter/nfnetlink_queue.c b/net/netfilter/nfnetlink_queue.c
> index 0dcc359..57eb02d 100644
> --- a/net/netfilter/nfnetlink_queue.c
> +++ b/net/netfilter/nfnetlink_queue.c
> @@ -905,13 +905,25 @@ static void free_entry(struct nf_queue_entry *entry)
>  dev_cmp(struct nf_queue_entry *entry, unsigned long ifindex)
>  {
>  #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
> -	int physinif, physoutif;
> +	struct net_device *physindev, *physoutdev;
> +	struct net_bridge_port *port;
>  
> -	physinif = nf_bridge_get_physinif(entry->skb);
> -	physoutif = nf_bridge_get_physoutif(entry->skb);
> -
> -	if (physinif == ifindex || physoutif == ifindex)
> -		return 1;
> +	physindev = nf_bridge_get_physindev(entry->skb);
> +	physoutdev = nf_bridge_get_physoutdev(entry->skb);
> +	if (physindev) {
> +		if (physindev->ifindex == ifindex)
> +			return 1;
> +		port = br_port_get_rcu(physindev);
> +		if (port && port->br->dev->ifindex == ifindex)
> +			return 1;
> +	}
> +	if (physoutdev) {
> +		if (physoutdev->ifindex == ifindex)
> +			return 1;
> +		port = br_port_get_rcu(physoutdev);
> +		if (port && port->br->dev->ifindex == ifindex)
> +			return 1;
> +	}

Either entry->state.in and entry->state.out point to the bridge
device, after this #endif.

>  #endif
>  	if (entry->state.in)
>  		if (entry->state.in->ifindex == ifindex)
> -- 
> 1.8.3.1
>