From 1ffe7100411a8b9015115ce124cd6c9c9da6f8e3 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Wed, 26 Oct 2022 09:52:36 +0200 Subject: [PATCH] netfilter: nf_tables: netlink notifier might race to release objects [ 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 Signed-off-by: Sasha Levin --- 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 f7a5b8414423d..8cd11a7e5a3e3 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -9824,6 +9824,8 @@ 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) && -- 2.30.2