From: Florian Westphal fw@strlen.de
[ Upstream commit 17a8f31bba7bac8cce4bd12bab50697da96e7710 ]
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 Signed-off-by: Sasha Levin sashal@kernel.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;