From: Pablo Neira Ayuso pablo@netfilter.org
[ Upstream commit d4bc8271db21ea9f1c86a1ca4d64999f184d4aae ]
commit release path is invoked via call_rcu and it runs lockless to release the objects after rcu grace period. The netlink notifier handler might win race to remove objects that the transaction context is still referencing from the commit release path.
Call rcu_barrier() to ensure pending rcu callbacks run to completion if the list of transactions to be destroyed is not empty.
Fixes: 6001a930ce03 ("netfilter: nftables: introduce table ownership") Reported-by: syzbot+8f747f62763bc6c32916@syzkaller.appspotmail.com Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/netfilter/nf_tables_api.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 5897afd12466..cc598504bc10 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -10030,6 +10030,8 @@ static int nft_rcv_nl_event(struct notifier_block *this, unsigned long event, nft_net = nft_pernet(net); deleted = 0; mutex_lock(&nft_net->commit_mutex); + if (!list_empty(&nf_tables_destroy_list)) + rcu_barrier(); again: list_for_each_entry(table, &nft_net->tables, list) { if (nft_table_has_owner(table) &&