netfilter: Cleanup nft_net->module_list from nf_tables_exit_net()

syzbot reported a warning like below [1]: WARNING: CPU: 3 PID: 9 at net/netfilter/nf_tables_api.c:10096 nf_tables_exit_net+0x71c/0x840 Modules linked in: CPU: 2 PID: 9 Comm: kworker/u8:0 Tainted: G W 6.1.0-rc3-00072-g8e5423e991e8 msm8953-mainline#47 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.fc36 04/01/2014 Workqueue: netns cleanup_net RIP: 0010:nf_tables_exit_net+0x71c/0x840 ... Call Trace: <TASK> ? __nft_release_table+0xfc0/0xfc0 ops_exit_list+0xb5/0x180 cleanup_net+0x506/0xb10 ? unregister_pernet_device+0x80/0x80 process_one_work+0xa38/0x1730 ? pwq_dec_nr_in_flight+0x2b0/0x2b0 ? rwlock_bug.part.0+0x90/0x90 ? _raw_spin_lock_irq+0x46/0x50 worker_thread+0x67e/0x10e0 ? process_one_work+0x1730/0x1730 kthread+0x2e5/0x3a0 ? kthread_complete_and_exit+0x40/0x40 ret_from_fork+0x1f/0x30 </TASK> In nf_tables_exit_net(), there is a case where nft_net->commit_list is empty but nft_net->module_list is not empty. Such a case occurs with the following scenario: 1. nfnetlink_rcv_batch() is called 2. nf_tables_newset() returns -EAGAIN and NFNL_BATCH_FAILURE bit is set to status 3. nf_tables_abort() is called with NFNL_ABORT_AUTOLOAD (nft_net->commit_list is released, but nft_net->module_list is not because of NFNL_ABORT_AUTOLOAD flag) 4. Jump to replay label 5. netlink_skb_clone() fails and returns from the function (this is caused by fault injection in the reproducer of syzbot) This patch fixes this issue by calling __nf_tables_abort() when nft_net->module_list is not empty in nf_tables_exit_net(). Fixes: eb014de ("netfilter: nf_tables: autoload modules from the abort path") Link: https://syzkaller.appspot.com/bug?id=802aba2422de4218ad0c01b46c9525cc9d4e4aa3 [1] Reported-by: syzbot+178efee9e2d7f87f5103@syzkaller.appspotmail.com Signed-off-by: Shigeru Yoshida <syoshida@redhat.com> Signed-off-by: Florian Westphal <fw@strlen.de>

Author: Shigeru Yoshida

net/netfilter/nf_tables_api.c

@@ -10090,7 +10090,8 @@ static void __net_exit nf_tables_exit_net(struct net *net)
 struct nftables_pernet *nft_net = nft_pernet(net);
 
 mutex_lock(&nft_net->commit_mutex);
-if (!list_empty(&nft_net->commit_list))
+if (!list_empty(&nft_net->commit_list) ||
+ !list_empty(&nft_net->module_list))
 __nf_tables_abort(net, NFNL_ABORT_NONE);
 __nft_release_tables(net);
 mutex_unlock(&nft_net->commit_mutex);