This is a note to let you know that I've just added the patch titled
netfilter: egress: silence egress hook lockdep splats
to the 5.16-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
netfilter-egress-silence-egress-hook-lockdep-splats.patch
and it can be found in the queue-5.16 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b11353fe05c45221072ab82c7e43b875daacafab
Author: Florian Westphal <fw@xxxxxxxxx>
Date: Mon Feb 28 04:18:05 2022 +0100
netfilter: egress: silence egress hook lockdep splats
[ 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@xxxxxxxxx>
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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;
