netfilter: nf_tables: hold mutex on netns pre_exit path

BugLink: https://bugs.launchpad.net/bugs/1981862
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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 93ede31990751f59c6ccada33ca6dcd3f904538d..db6ec4f110dd32ff207f536a495d9be12bfb2464 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -9760,7 +9760,11 @@ 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)