From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org
Subject: [PATCH net 3/8] netfilter: egress: silence egress hook lockdep splats
Date: Tue, 1 Mar 2022 22:53:32 +0100 [thread overview]
Message-ID: <20220301215337.378405-4-pablo@netfilter.org> (raw)
In-Reply-To: <20220301215337.378405-1-pablo@netfilter.org>
From: Florian Westphal <fw@strlen.de>
Netfilter assumes its called with rcu_read_lock held, but in egress
hook case it may be called with BH readlock.
This triggers lockdep splat.
In order to avoid to change all rcu_dereference() to
rcu_dereference_check(..., rcu_read_lock_bh_held()), wrap nf_hook_slow
with read lock/unlock pair.
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
include/linux/netfilter_netdev.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/include/linux/netfilter_netdev.h b/include/linux/netfilter_netdev.h
index b4dd96e4dc8d..e6487a691136 100644
--- a/include/linux/netfilter_netdev.h
+++ b/include/linux/netfilter_netdev.h
@@ -101,7 +101,11 @@ static inline struct sk_buff *nf_hook_egress(struct sk_buff *skb, int *rc,
nf_hook_state_init(&state, NF_NETDEV_EGRESS,
NFPROTO_NETDEV, dev, NULL, NULL,
dev_net(dev), NULL);
+
+ /* nf assumes rcu_read_lock, not just read_lock_bh */
+ rcu_read_lock();
ret = nf_hook_slow(skb, &state, e, 0);
+ rcu_read_unlock();
if (ret == 1) {
return skb;
--
2.30.2
next prev parent reply other threads:[~2022-03-01 21:53 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-01 21:53 [PATCH net 0/8] Netfilter fixes for net Pablo Neira Ayuso
2022-03-01 21:53 ` [PATCH net 1/8] netfilter: nf_tables: prefer kfree_rcu(ptr, rcu) variant Pablo Neira Ayuso
2022-03-01 23:30 ` patchwork-bot+netdevbpf
2022-03-01 21:53 ` [PATCH net 2/8] netfilter: fix use-after-free in __nf_register_net_hook() Pablo Neira Ayuso
2022-03-01 21:53 ` Pablo Neira Ayuso [this message]
2022-03-01 21:53 ` [PATCH net 4/8] netfilter: nf_queue: don't assume sk is full socket Pablo Neira Ayuso
2022-03-01 21:53 ` [PATCH net 5/8] selftests: netfilter: add nfqueue TCP_NEW_SYN_RECV socket race test Pablo Neira Ayuso
2022-03-01 21:53 ` [PATCH net 6/8] netfilter: nf_queue: fix possible use-after-free Pablo Neira Ayuso
2022-03-01 21:53 ` [PATCH net 7/8] netfilter: nf_queue: handle socket prefetch Pablo Neira Ayuso
2022-03-01 21:53 ` [PATCH net 8/8] net/sched: act_ct: Fix flow table lookup failure with no originating ifindex Pablo Neira Ayuso
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