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Date:   Thu, 5 Mar 2020 13:10:12 +0100
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     Florian Westphal <fw@...len.de>
Cc:     netfilter-devel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
        netdev@...r.kernel.org,
        syzbot+a2ff6fa45162a5ed4dd3@...kaller.appspotmail.com
Subject: Re: [PATCH nf] netfilter: nf_tables: free flowtable hooks on hook
 register error

On Mon, Mar 02, 2020 at 09:58:50PM +0100, Florian Westphal wrote:
> If hook registration fails, the hooks allocated via nft_netdev_hook_alloc
> need to be freed.
> 
> We can't change the goto label to 'goto 5' -- while it does fix the memleak
> it does cause a warning splat from the netfilter core (the hooks were not
> registered).

It seems test/shell crashes after this, looking. It works after
reverting.

> Fixes: 3f0465a9ef02 ("netfilter: nf_tables: dynamically allocate hooks per net_device in flowtables")
> Reported-by: syzbot+a2ff6fa45162a5ed4dd3@...kaller.appspotmail.com
> Signed-off-by: Florian Westphal <fw@...len.de>
> ---
>  net/netfilter/nf_tables_api.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
> index d1318bdf49ca..bb064aa4154b 100644
> --- a/net/netfilter/nf_tables_api.c
> +++ b/net/netfilter/nf_tables_api.c
> @@ -6300,8 +6300,13 @@ static int nf_tables_newflowtable(struct net *net, struct sock *nlsk,
>  		goto err4;
>  
>  	err = nft_register_flowtable_net_hooks(ctx.net, table, flowtable);
> -	if (err < 0)
> +	if (err < 0) {
> +		list_for_each_entry_safe(hook, next, &flowtable->hook_list, list) {
> +			list_del_rcu(&hook->list);
> +			kfree_rcu(hook, rcu);
> +		}
>  		goto err4;
> +	}
>  
>  	err = nft_trans_flowtable_add(&ctx, NFT_MSG_NEWFLOWTABLE, flowtable);
>  	if (err < 0)
> -- 
> 2.24.1
> 

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