netfilter: nf_tables: hold mutex on netns pre_exit path

commit 3923b1e4406680d57da7e873da77b1683035d83f upstream.

clean_net() runs in workqueue while walking over the lists, grab mutex.

Fixes: 767d1216bff8 ("netfilter: nftables: fix possible UAF over chains from packet path in netns")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index ee4edebe6124f5e0867c7d84ec87198ce49f0e2b..f274716e024d6f31d55b18eff12a869cfe7ae215 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -9746,7 +9746,11 @@ static int __net_init nf_tables_init_net(struct net *net)
 
 static void __net_exit nf_tables_pre_exit_net(struct net *net)
 {
+       struct nftables_pernet *nft_net = nft_pernet(net);
+
+       mutex_lock(&nft_net->commit_mutex);
        __nft_release_hooks(net);
+       mutex_unlock(&nft_net->commit_mutex);
 }
 
 static void __net_exit nf_tables_exit_net(struct net *net)