netdev - [PATCH nf] netfilter: nf_tables: free flowtable hooks on hook register error

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Date:   Mon,  2 Mar 2020 21:58:50 +0100
From:   Florian Westphal <fw@...len.de>
To:     <netfilter-devel@...r.kernel.org>
Cc:     syzkaller-bugs@...glegroups.com, netdev@...r.kernel.org,
        Florian Westphal <fw@...len.de>,
        syzbot+a2ff6fa45162a5ed4dd3@...kaller.appspotmail.com
Subject: [PATCH nf] netfilter: nf_tables: free flowtable hooks on hook register error

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).

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